全文获取类型
收费全文 | 10767篇 |
免费 | 826篇 |
国内免费 | 47篇 |
专业分类
耳鼻咽喉 | 116篇 |
儿科学 | 269篇 |
妇产科学 | 159篇 |
基础医学 | 1204篇 |
口腔科学 | 276篇 |
临床医学 | 1156篇 |
内科学 | 1877篇 |
皮肤病学 | 98篇 |
神经病学 | 901篇 |
特种医学 | 571篇 |
外科学 | 1986篇 |
综合类 | 129篇 |
一般理论 | 5篇 |
预防医学 | 1054篇 |
眼科学 | 169篇 |
药学 | 935篇 |
中国医学 | 6篇 |
肿瘤学 | 729篇 |
出版年
2023年 | 46篇 |
2022年 | 95篇 |
2021年 | 266篇 |
2020年 | 161篇 |
2019年 | 240篇 |
2018年 | 298篇 |
2017年 | 231篇 |
2016年 | 237篇 |
2015年 | 285篇 |
2014年 | 403篇 |
2013年 | 531篇 |
2012年 | 830篇 |
2011年 | 744篇 |
2010年 | 426篇 |
2009年 | 349篇 |
2008年 | 579篇 |
2007年 | 634篇 |
2006年 | 555篇 |
2005年 | 591篇 |
2004年 | 526篇 |
2003年 | 507篇 |
2002年 | 427篇 |
2001年 | 137篇 |
2000年 | 121篇 |
1999年 | 154篇 |
1998年 | 119篇 |
1997年 | 112篇 |
1996年 | 89篇 |
1995年 | 83篇 |
1994年 | 71篇 |
1993年 | 65篇 |
1992年 | 85篇 |
1991年 | 86篇 |
1990年 | 90篇 |
1989年 | 91篇 |
1988年 | 93篇 |
1987年 | 79篇 |
1986年 | 83篇 |
1985年 | 78篇 |
1984年 | 91篇 |
1983年 | 72篇 |
1982年 | 62篇 |
1981年 | 65篇 |
1980年 | 58篇 |
1979年 | 59篇 |
1978年 | 70篇 |
1977年 | 59篇 |
1976年 | 72篇 |
1974年 | 56篇 |
1973年 | 60篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
Analysis of human papillomavirus types in exophytic condylomata acuminata by hybrid capture and Southern blot techniques. 总被引:3,自引:3,他引:3
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Exophytic condylomata acuminata of the external genitalia of 40 patients were analyzed for human papillomavirus (HPV) DNA by the Southern blot and hybrid capture methods. All lesions were initially analyzed by the Southern blot method by using a mixture of HPV type 6, 11, 16, and 18 whole genomic probes. Southern blots demonstrated characteristic PstI restriction patterns of HPV type 6, 11, or 16 in all but one lesion. HPV 6 subtypes accounted for 28 of 39 HPV-positive lesions. Twenty-seven of these 28 lesions contained HPV type 6a, and 1 lesion contained HPV type 6c. Eight lesions contained HPV type 11 and three contained HPV type 16. Two of the three condylomata acuminata containing HPV type 16 were obtained from solid-organ transplant recipients receiving immunosuppressive medications. The third lesion containing HPV type 16 was a typical exophytic condyloma acuminatum from a woman with previously resected vulvar carcinoma. The hybrid capture assay detected HPV DNAs in all lesions except the Southern blot-negative lesion. Twenty-five lesions were positive for the A probe only (HPV types 6 and 11 and related types). All of these lesions were found to contain HPV type 6 or 11 sequences in the Southern blot assay. The remaining 14 lesions were positive for both the A probe and the B probe (HPV types 16 and 18 and related types). The strongest signal in these 14 lesions by the hybrid capture assay was consistent with the result of the Southern blot assay in all but one case. We conclude that (i) HPV type 6a is the most common type found in these lesions, (ii) HPV type 16 may be present more often in exophytic condylomata acuminata from immunosuppressed individuals, (iii) hybrid capture is a useful tool for documenting the presence of HPV sequences in DNAs from exophytic condylomata acuminata, and (iv) in samples containing multiple HPV types, hybrid capture allows detection of minority HPV types. 相似文献
72.
The histone modification pattern of active genes revealed through genome-wide chromatin analysis of a higher eukaryote 总被引:35,自引:2,他引:35
下载免费PDF全文
![点击此处可从《Genes & development》网站下载免费的PDF全文](/ch/ext_images/free.gif)
73.
Perturbation of hyaluronan interactions inhibits malignant properties of glioma cells 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Malignant progression of gliomas is characterized by acquisition of inappropriate growth and invasive properties. In vitro, these malignant properties are reflected in, and measured by, the ability to grow in an anchorage-independent manner and to invade artificial extracellular matrices. The results of numerous studies have suggested that the extracellular and pericellular matrix polysaccharide, hyaluronan, plays an important role in these attributes of malignant cancer cells. However, with respect to glioma cells, most studies have addressed the effect of exogenously added hyaluronan rather than the function of endogenous tumor cell-associated hyaluronan. In this study we manipulate hyaluronan-glioma cell interactions by two methods. The first is administration of small hyaluronan oligosaccharides that compete for endogenous hyaluronan polymer interactions, resulting in attenuation of hyaluronan-induced signaling. The second is overexpression of soluble hyaluronan-binding proteins that act as a competitive sink for interaction with endogenous hyaluronan, again leading to attenuated signaling. We find that both treatments inhibit anchorage-independent growth, as measured by colony formation in soft agar, and invasiveness, as measured by penetration of reconstituted basement membrane matrices. Based on our findings, we conclude that endogenous hyaluronan interactions are essential for these two fundamental malignant properties of glioma cells. 相似文献
74.
Humoral immunity to commensal oral bacteria in human infants: salivary secretory immunoglobulin A antibodies reactive with Streptococcus mitis biovar 1, Streptococcus oralis, Streptococcus mutans, and Enterococcus faecalis during the first two years of life
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Cole MF Bryan S Evans MK Pearce CL Sheridan MJ Sura PA Wientzen RL Bowden GH 《Infection and immunity》1999,67(4):1878-1886
Secretory immunoglobulin A (SIgA) antibodies reactive with the pioneer oral streptococci Streptococcus mitis biovar 1 and Streptococcus oralis, the late oral colonizer Streptococcus mutans, and the pioneer enteric bacterium Enterococcus faecalis in saliva samples from 10 human infants from birth to age 2 years were analyzed. Low levels of salivary SIgA1 and SIgA2 antibodies reactive with whole cells of all four species were detected within the first month after birth, even though S. mutans and E. faecalis were not recovered from the mouths of the infants during the study period. Although there was a fivefold increase in the concentration of SIgA between birth and age 2 years, there were no differences between the concentrations of SIgA1 and SIgA2 antibodies reactive with the four species over this time period. When the concentrations of SIgA1 and SIgA2 antibodies reactive with all four species were normalized to the concentrations of SIgA1 and SIgA2 in saliva, SIgA1 and SIgA2 antibodies reactive with these bacteria showed a significant decrease from birth to 2 years of age. Adsorption of each infant's saliva with cells of one species produced a dramatic reduction of antibodies recognizing the other three species. Sequential adsorption of saliva samples removed all SIgA antibody to the bacteria, indicating that the SIgA antibodies were directed to antigens shared by all four species. The induction by the host of a limited immune response to common antigens that are likely not involved in adherence may be among the mechanisms that commensal streptococci employ to persist in the oral cavity. 相似文献
75.
Development of hatching blastocysts from immature human oocytes following in-vitro maturation and fertilization using a co-culture system 总被引:8,自引:0,他引:8
Hwu YM; Lee RK; Chen CP; Su JT; Chen YW; Lin SP 《Human reproduction (Oxford, England)》1998,13(7):1916-1921
Recently, in-vitro maturation (IVM) of immature human oocytes recovered
from non-stimulated follicles has been applied in the treatment of
infertility. However, in previous reports, very few embryos cultured in
conventional medium have reached the expanded blastocyst stage following
in-vitro maturation and fertilization (IVM/IVF). The objective of this
study was to investigate whether the developmental competence of human
embryos following IVM/IVF could be enhanced by the use of a human ampullary
cell co-culture system. Immature human oocytes were aspirated from small
follicles at Caesarean section and then cultured in medium containing human
menopausal gonadotrophin for 36 to 48 h, followed by insemination. Zygotes
were randomly cultured either in conventional culture medium alone or in
the co-culture system. Of 48 embryos cultured in conventional medium alone,
all arrested at the 2-16- cell stage on day 3 after insemination. Of 46
embryos cultured in the co-culture system, 26 embryos (56.5%) arrested at
the 2-16-cell stage. Six embryos (13%) developed to the morula stage.
Fourteen embryos (30.4%) developed to expanded blastocysts and two
blastocysts were hatching on day 7 after insemination. We conclude that
co-culture significantly enhances the development of blastocysts in embryos
resulting from IVM/IVF.
相似文献
76.
Comparison of agar disk diffusion, microdilution broth, and agar dilution for testing antimicrobial susceptibility of coagulase-negative staphylococci. 总被引:1,自引:3,他引:1
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
J A Smith D A Henry A M Bourgault L Bryan G J Harding D J Hoban G B Horsman T Marrie P Turgeon 《Journal of clinical microbiology》1987,25(9):1741-1746
A collection of 120 oxacillin-susceptible and 120 oxacillin-resistant coagulase-negative staphylococci (CNS) from six tertiary care hospital laboratories were tested by agar disk diffusion, three microdilution broth systems (Sensititre, Dynatech, and Alpkem), and the Vitek AutoMicrobic system for comparison with reference agar dilution results. The antimicrobial agents tested were oxacillin, cefazolin, cefotaxime, cefuroxime, cefamandole, fusidic acid, rifampin, and vancomycin. Incubation was at 30 or 35 degrees C for 24, 48, and 72 h. The broth media were supplemented with 2% NaCl for some antimicrobial agents, and the agar dilution method was used with and without the addition of 4% NaCl. The CNS were identified to species by the method of Kloos and Schleifer. The results showed a lack of concordance between two hospitals with respect to oxacillin susceptibility testing by agar dilution with no NaCl supplement. The reasons are not clear but may be related to variations in media. The 4% NaCl supplement or extended incubation to 48 h eliminated this difference. The cefazolin and cefotaxime susceptibility results in the agar disk diffusion test were unreliable if accepted at face value. Cefamandole testing correlated well with the reference method regardless of the method used, and salt supplementation is not recommended. Most of the oxacillin-resistant CNS were resistant to the other beta-lactam drugs except cefamandole. Of 22 CNS resistant to cefamandole, 21 were S. haemolyticus. 相似文献
77.
Transfer of Tumor Necrosis Factor-α to Rat Lung Induces Severe Pulmonary Inflammation and Patchy Interstitial Fibrogenesis with Induction of Transforming Growth Factor-β1 and Myofibroblasts
下载免费PDF全文
![点击此处可从《The American journal of pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Patricia J. Sime Robert A. Marr David Gauldie Zhou Xing Bryan R. Hewlett Frank L. Graham Jack Gauldie 《The American journal of pathology》1998,153(3):825-832
Tumor necrosis factor-α is up-regulated in a variety of different human immune-inflammatory and fibrotic pulmonary pathologies. However, its precise role in these pathologies and, in particular, the mechanism(s) by which it may induce fibrogenesis are not yet elucidated. Using a replication-deficient adenovirus to transfer the cDNA of tumor necrosis factor-α to rat lung, we have been able to study the effect of transient but prolonged (7 to 10 days) overexpression of tumor necrosis factor-α in normal adult pulmonary tissue. We have demonstrated that local overexpression resulted in severe pulmonary inflammation with significant increases in neutrophils, macrophages, and lymphocytes and, to a lesser extent, eosinophils, with a peak at day 7. By day 14, the inflammatory cell accumulation had declined, and fibrogenesis became evident, with fibroblast accumulation and deposition of extracellular matrix proteins. Fibrotic changes were patchy but persisted to beyond day 64. To elucidate the mechanism underlying this fibrogenesis, we examined bronchoalveolar fluids for the presence of the fibrogenic cytokine transforming growth factor-β1 and tissues for induction of α-smooth muscle actin-rich myofibroblasts. Transforming growth factor-β1 was transiently elevated from day 7 (peak at day 14) immediately preceding the onset of fibrogenesis. Furthermore, there was a striking accumulation of myofibroblasts from day 7, with the most extensive and intense immunostaining at day 14, ie, coincident with the up-regulation of transforming growth factor-β1 and onset of fibrogenesis. Thus, we have provided a model of tumor necrosis factor-α-mediated pulmonary inflammation and fibrosis in normal adult lung, and we suggest that the fibrogenesis may be mediated by the secondary up-regulation of transforming growth factor-β1 and induction of pulmonary myofibroblasts. 相似文献
78.
Detection of genetic alterations in primary bladder carcinoma with dual-color and multiplex fluorescence in situ hybridization 总被引:4,自引:0,他引:4
Stamouli MI Panani AD Ferti AD Petraki C Oliver RT Raptis SA Young BD 《Cancer Genetics and Cytogenetics》2004,149(2):107-113
Cytogenetic studies of bladder cancer have shown several nonrandom aberrations. Numerical aberrations of both sex chromosomes were investigated in 32 primary bladder tumors with bicolor fluorescence in situ hybridization (FISH). Loss of chromosome Y and overrepresentation of chromosome X were observed in subgroups of male patients. Chromosome X was represented normally in female patients. Two of the above primary bladder tumors, a transitional cell carcinoma (TCC) and an adenocarcinoma, were further analyzed with both multiplex FISH (24-color M-FISH) and G-banding. Both cases exhibited 1) common breakpoints on 5q11 approximately q12 and 15q24; 2) involvement of the pericentromeric area of chromosome 13; 3) structural abnormalities of chromosomes 8 and 17, with loss of material on the short arm; 4) structural abnormalities involving chromosome 11; and 5) loss of chromosome Y. The TCC case also exhibited structural abnormalities of chromosome 9, resulting in loss of 9q. The combined G-banding and M-FISH findings could help reveal regions potentially involved in bladder tumorigenesis. 相似文献
79.
The ratio of 2nd to 4th digit length: a predictor of sperm numbers and concentrations of testosterone, luteinizing hormone and oestrogen 总被引:19,自引:2,他引:19
Manning JT; Scutt D; Wilson J; Lewis-Jones DI 《Human reproduction (Oxford, England)》1998,13(11):3000-3004
The differentiation of the urinogenital system and the appendicular
skeleton in vertebrates is under the control of Hox genes. The common
control of digit and gonad differentiation raises the possibility that
patterns of digit formation may relate to spermatogenesis and hormonal
concentrations. This work was concerned with the ratio between the length
of the 2nd and 4th digit (2D:4D) in humans. We showed that (i) 2D:4D in
right and left hands has a sexually dimorphic pattern; in males mean 2D:4D
= 0.98, i.e. the 4th digit tended to be longer than the 2nd and in females
mean 2D:4D = 1.00, i.e. the 2nd and 4th digits tended to be of equal
length. The dimorphism is present from at least age 2 years and 2D:4D is
probably established in utero; (ii) high 2D:4D ratio in right hands was
associated with germ cell failure in men (P = 0.04); (iii) sperm number was
negatively related to 2D:4D in the right hand (P = 0.004); (iv) in men
testosterone concentrations were negatively related to right hand 2D:4D and
in women and men LH (right hand), oestrogen (right and left hands) and
prolactin (right hand) concentrations were positively correlated with 2D:4D
ratio and (v) 2D:4D ratio in right hands remained positively related to
luteinizing hormone and oestrogen after controlling for sex, age, height
and weight.
相似文献
80.