全文获取类型
收费全文 | 45128篇 |
免费 | 2729篇 |
国内免费 | 258篇 |
专业分类
耳鼻咽喉 | 389篇 |
儿科学 | 1300篇 |
妇产科学 | 1201篇 |
基础医学 | 5951篇 |
口腔科学 | 938篇 |
临床医学 | 4497篇 |
内科学 | 9851篇 |
皮肤病学 | 882篇 |
神经病学 | 4820篇 |
特种医学 | 1500篇 |
外科学 | 5909篇 |
综合类 | 175篇 |
一般理论 | 19篇 |
预防医学 | 3369篇 |
眼科学 | 767篇 |
药学 | 2795篇 |
1篇 | |
中国医学 | 85篇 |
肿瘤学 | 3666篇 |
出版年
2024年 | 70篇 |
2023年 | 520篇 |
2022年 | 999篇 |
2021年 | 1807篇 |
2020年 | 1060篇 |
2019年 | 1487篇 |
2018年 | 1703篇 |
2017年 | 1193篇 |
2016年 | 1339篇 |
2015年 | 1545篇 |
2014年 | 2125篇 |
2013年 | 2645篇 |
2012年 | 3917篇 |
2011年 | 3906篇 |
2010年 | 1975篇 |
2009年 | 1846篇 |
2008年 | 3121篇 |
2007年 | 3008篇 |
2006年 | 2707篇 |
2005年 | 2679篇 |
2004年 | 2237篇 |
2003年 | 2000篇 |
2002年 | 1773篇 |
2001年 | 230篇 |
2000年 | 160篇 |
1999年 | 231篇 |
1998年 | 301篇 |
1997年 | 222篇 |
1996年 | 198篇 |
1995年 | 183篇 |
1994年 | 155篇 |
1993年 | 123篇 |
1992年 | 88篇 |
1991年 | 77篇 |
1990年 | 63篇 |
1989年 | 44篇 |
1988年 | 44篇 |
1987年 | 37篇 |
1986年 | 32篇 |
1985年 | 33篇 |
1984年 | 40篇 |
1983年 | 22篇 |
1982年 | 40篇 |
1981年 | 24篇 |
1980年 | 21篇 |
1979年 | 10篇 |
1978年 | 13篇 |
1977年 | 13篇 |
1976年 | 11篇 |
1972年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Moore VA Varela AS Yabsley MJ Davidson WR Little SE 《Journal of clinical microbiology》2003,41(1):424-427
To determine if white-tailed deer may serve as a reservoir host for Borrelia lonestari, we used a nested PCR for the Borrelia flagellin gene to evaluate blood samples collected from deer from eight southeastern states. Seven of 80 deer (8.7%) from 5 of 17 sites (29.4%) had sequence-confirmed evidence of a B. lonestari flagellin gene by PCR, indicating that deer are infected with B. lonestari or another closely related Borrelia species. Our findings expand the known geographic range of B. lonestari and provide the first evidence of this organism in a vertebrate other than humans. 相似文献
102.
Fascin,an actin-bundling protein,modulates colonic epithelial cell invasiveness and differentiation in vitro 总被引:18,自引:0,他引:18 下载免费PDF全文
Jawhari AU Buda A Jenkins M Shehzad K Sarraf C Noda M Farthing MJ Pignatelli M Adams JC 《The American journal of pathology》2003,162(1):69-80
In epithelial tissue, cell-matrix and cell-cell adhesive interactions have important roles in the normal organization and stabilization of the cell layer. The malignant conversion of epithelial cells involves alterations in the expression and function of these adhesion systems that enable a switch to a migratory phenotype in tumor invasion and metastasis. Fascin is an actin-crosslinking protein that is found in the core actin bundles of cell-surface spikes and projections that are implicated in cell motility. We demonstrate that fascin is not detectable in normal colonic epithelium, but is dramatically up-regulated in colorectal adenocarcinoma. To test the hypothesis that fascin could participate in tumor invasive behavior, we developed a cell culture model to examine the effect of fascin expression on the adhesive interactions, invasiveness, and differentiation of colonic epithelial cells. We report marked effects on the organization of cell-surface protrusions, actin cytoskeleton, and focal adhesions in the absence of alterations in the protein levels of the major components of these structures. These effects correlate with alterations in cell movements on two-dimensional matrix, and increased invasiveness in three-dimensional matrix. The cells also show increased proliferation and decreased capacity for normal glandular differentiation in collagen gels. We propose that up-regulation of fascin, by promoting the formation of protrusive, actin-based, cell-motility structures, could be a significant component in the acquisition of invasive phenotype in colonic carcinoma. 相似文献
103.
Willinger B Kopetzky G Harm F Apfalter P Makristathis A Berer A Bankier A Winkler S 《Journal of clinical microbiology》2004,42(1):478-480
Disseminated infection with the coelomycetous fungus Nattrassia mangiferae is a very rare disease affecting only the immunocompromised host. We report the first case of a disseminated infection with spondylodiscitis and granular skin lesions due to N. mangiferae in a renal transplant patient. 相似文献
104.
The UL41 gene of the HSZP strain of herpes simplex virus type 1 (HSV-1) defective with respect to the early shutoff of host
protein synthesis was sequenced and compared with the corresponding HSV-1 strain KOS and 17 gene sequences. In comparison
with strain 17, nine mutations (base changes) were HSZP specific, five KOS specific and four were common for both strains.
Nine mutations caused codon changes. Three of these mapped to the nonconserved regions and the others to the conserved regions
of the functional map of UL4l gene. One KOS specific mutation mapped to the region responsible for the binding of the virion
host shutoff (vhs) protein to the alpha-transinducing factor (VP16). The possible relationship between mutations and host
shutoff function is discussed. The nucleotide sequence data of the UL41 gene of HSZP and KOS have been submitted to the Genbank
nucleotide database and have been assigned the accesion numbers Z72337 and Z72338.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
105.
Though much research about the public's views of scientists, genetic research and its moral, ethical, and social implications exists, little has been done to investigate how scientists view their own role(s) in public discussions and policy formation related to genetic research and technologies. We interviewed 20 academic geneticists in the United States about their perceptions of the roles they and others (e.g., professional societies, the public, ethicists, and elected officials) do and should play in the formation of science policy, the communication of science to the public, and the public discussions of moral and ethical issues raised by scientific advances. The participants in our study thought that scientists should be more actively involved in public outreach and science policy formation, but frequently they felt ill-equipped and unsupported by their peers and institutions to pursue these activities. Furthermore, many were skeptical of or did not trust elected officials--who they consider uninformed about the issues and too driven by political agendas--to formulate sound science policy. They do, however, have faith in the ability of scientific societies to influence policy effectively, and some thought that societies should play a larger role, both in science policy and as a liaison between scientists and the public. Finally, participants offered suggestions for increasing the involvement and influence of scientists in science-policy formation and public discourse. 相似文献
106.
Cytomegalovirus (CMV) replication in non-proliferating cells requires the coordinated expression of the host enzymes responsible for deoxyribonucleotide synthesis. Thymidylate synthase (TS) is an essential cellular enzyme that catalyzes de novo synthesis of thymidylic acid (dTMP). In this report we show that murine CMV (MCMV) replication and DNA synthesis are inhibited in quiescent 3T6 fibroblasts by raltitrexed, a quinazoline-based folate analog that specifically inhibits TS. This antiviral activity was abrogated in LU3-7 cells, a 3T6 derivative that overproduces TS by about 50-fold. These observations indicate that the anticytomegaloviral activity of raltitrexed is associated with TS inhibition and suggest that cellular TS activity is required for efficient CMV replication in quiescent cells. 相似文献
107.
Andrea Facchini Adriana Rita Mariani Stefano Papa Erminia Mariani Francesco Antonio Manzoli 《Immunology letters》1984,8(4):207-210
Human T lymphocyte subsets, identified by means of OKT3, 4 and 8 monoclonal antibodies, were isolated by a fluorescence activated cell sorter (FACS IV) and analyzed for distribution of alpha-naphthyl acetate esterase (ANAE) activity. As compared to OKT8+ lymphocytes a higher proportion of OKT4+ lymphocytes was ANAE-positive exibiting a spot or dot-like pattern in the cytoplasm. OKT8 and 4 positive subsets showed a similar ANAE distribution in diffuse granular form. Although OKT4 and OKT8 populations presented a different ANAE dot-like reactivity, this marker did not allow as clear a distinction between them as that reported for TG and TM lymphocytes. 相似文献
108.
Andrea Fleig Peter C. Ruben Martin D. Rayner 《Pflügers Archiv : European journal of physiology》1994,427(5-6):399-405
Na currents recorded from inside-out macropatches excised from Xenopus oocytes expressing the subunit of the rat brain Na channel IIA show at least two distinguishable components in their inactivation time course, with time constants differing about tenfold (
h1 = approx. 150 s and
h2 = approx. 2 ms). In excised patches, the inactivation properties of Na currents changed with time, favoring the faster inactivation kinetics. Analysis of the fast and slow current kinetics shows that only the relative magnitudes of
h1 and
h2 components are altered without significant changes in the time constants of activation or inactivation. In addition, voltage dependence of both activation and steady-state inactivation of Na currents are shifted to more negative potentials in patches with predominantly fast inactivation, although reversal potentials and valences remained unaltered. We conclude that the two inactivation modes discerned in this study are conferred by two states of Na channel the interconversion of which are regulated by an as yet unknown mechanism that seems to involve cytosolic factors. 相似文献
109.
Maria L. Dentici Vittorio Maglione Emanuele Agolini Gino Catena Rossella Capolino Valentina Lanari Antonio Novelli Lorenzo Sinibaldi Davide Vecchio Michaela V. Gonfiantini Marina Macchiaiolo Maria C. Digilio Bruno Dallapiccola Andrea Bartuli 《American journal of medical genetics. Part A》2020,182(8):1977-1984
The tubulinopathies refer to a wide range of brain malformations caused by mutations in one of the seven genes encoding different tubulin's isotypes. The β‐tubulin isotype III (TUBB3) gene has a primary function in nervous system development and axon generation and maintenance, due to its neuron‐specific expression pattern. A recurrent heterozygous mutation, c.1228G > A; p.E410K, in TUBB3 gene is responsible of a rare disorder clinically characterized by congenital fibrosis of the extraocular muscle type 3 (CFEOM3), intellectual disability and a wide range of neurological and endocrine abnormalities. Other mutations have been described spanning the entire gene and genotype–phenotype correlations have been proposed. We report on a 3‐year‐old boy in whom clinical exome sequencing allowed to identify a de novo TUBB3 E410K mutation as the molecular cause underlying a complex phenotype characterized by a severe bilateral palpebral ptosis refractory to eye surgery, psychomotor delay, absent speech, hypogonadism, celiac disease, and cyclic vomiting. Brain MRI revealed thinning of the corpus callosum with no evidence of malformation cortical dysplasia. We reviewed available records of patients with TUBB3 E410K mutation and compared their phenotype with the clinical outcome of patients with other mutations in TUBB3 gene. The present study confirms that TUBB3 E410K results in a clinically recognizable phenotype, unassociated to the distinct cortical dysplasia caused by other mutations in the same gene. Early molecular characterization of TUBB3 E410K syndrome is critical for targeted genetic counseling and prompt prospective care in term of neurological, ophthalmological, endocrine, and gastrointestinal follow‐up. 相似文献
110.
Detection of methicillin-resistant Staphylococcus aureus and simultaneous confirmation by automated nucleic acid extraction and real-time PCR 下载免费PDF全文
Grisold AJ Leitner E Mühlbauer G Marth E Kessler HH 《Journal of clinical microbiology》2002,40(7):2392-2397
A molecular assay for the simultaneous detection of a Staphylococcus aureus-specific gene and the mecA gene, responsible for the resistance to methicillin in staphylococci, was evaluated. The assay included an automated DNA extraction protocol conducted with a MagNA Pure instrument and real-time PCR conducted with a LightCycler instrument. The performance and robustness of the assay were evaluated for a suspension of methicillin-resistant S. aureus (MRSA) strain with a turbidity equivalent to a McFarland standard of 0.5, which was found to be the ideal working concentration. The specificity of the new molecular assay was tested with a panel of 30 gram-negative and gram-positive bacterial strains other than MRSA. No cross-reactivity was observed. In a clinical study, 109 isolates of MRSA were investigated. All clinical MRSA isolates gave positive results for the S. aureus-specific genomic target, and all but one were positive for the mecA gene. In conclusion, the new molecular assay was found to be quick, robust, and laborsaving, and it proved to be suitable for a routine molecular diagnostic laboratory. 相似文献