全文获取类型
收费全文 | 3148篇 |
免费 | 149篇 |
国内免费 | 15篇 |
专业分类
耳鼻咽喉 | 33篇 |
儿科学 | 122篇 |
妇产科学 | 50篇 |
基础医学 | 335篇 |
口腔科学 | 92篇 |
临床医学 | 267篇 |
内科学 | 583篇 |
皮肤病学 | 37篇 |
神经病学 | 264篇 |
特种医学 | 329篇 |
外科学 | 349篇 |
综合类 | 37篇 |
一般理论 | 3篇 |
预防医学 | 171篇 |
眼科学 | 25篇 |
药学 | 190篇 |
肿瘤学 | 425篇 |
出版年
2022年 | 19篇 |
2021年 | 25篇 |
2020年 | 26篇 |
2019年 | 24篇 |
2018年 | 24篇 |
2017年 | 36篇 |
2016年 | 40篇 |
2015年 | 59篇 |
2014年 | 73篇 |
2013年 | 101篇 |
2012年 | 104篇 |
2011年 | 129篇 |
2010年 | 84篇 |
2009年 | 90篇 |
2008年 | 94篇 |
2007年 | 112篇 |
2006年 | 97篇 |
2005年 | 113篇 |
2004年 | 112篇 |
2003年 | 95篇 |
2002年 | 100篇 |
2001年 | 86篇 |
2000年 | 87篇 |
1999年 | 105篇 |
1998年 | 75篇 |
1997年 | 73篇 |
1996年 | 62篇 |
1995年 | 66篇 |
1994年 | 71篇 |
1993年 | 45篇 |
1992年 | 70篇 |
1991年 | 56篇 |
1990年 | 63篇 |
1989年 | 57篇 |
1988年 | 72篇 |
1987年 | 53篇 |
1986年 | 93篇 |
1985年 | 74篇 |
1984年 | 37篇 |
1983年 | 51篇 |
1982年 | 31篇 |
1981年 | 29篇 |
1980年 | 19篇 |
1979年 | 36篇 |
1978年 | 31篇 |
1977年 | 27篇 |
1976年 | 27篇 |
1975年 | 27篇 |
1972年 | 21篇 |
1969年 | 18篇 |
排序方式: 共有3312条查询结果,搜索用时 31 毫秒
31.
A comparison of Skirrow's, Butzler's, Blaser's, Campy-BAP and Preston media for Campylobacter spp was made using human, animal and environmental specimens. Butzler's medium gave the lowest isolation rate and Preston medium, which was the most selective, the highest isolation rate. Enrichment culture using Preston enrichment broth gave a higher isolation rate than direct plating onto Preston medium. 相似文献
32.
Dynamic patterns of expression of BMP isoforms 2, 4, 5, 6, and 7 during chicken heart development 总被引:2,自引:0,他引:2
Somi S Buffing AA Moorman AF Van Den Hoff MJ 《The anatomical record. Part A, Discoveries in molecular, cellular, and evolutionary biology》2004,279(1):636-651
Bone morphogentic proteins (BMPs) play an important role in cardiac development. Using an in vitro explant analysis, we show that BMPs are crucial for myocardium formation. As a first approach to identify which BMP may be involved in myocardium formation in intra- and extracardiac mesenchyme in vivo, a survey of the expression patterns of BMP2, -4, -5, -6, and -7 mRNA is prepared by in situ hybridization in chicken embryonic hearts from HH5 to 44. During recruitment of mesodermal cells to the outflow tract myocardium (HH10-23), BMP2, -4, -5, and -7 mRNA are expressed in the distal myocardial border and the flanking mesenchyme. After completion, BMP2 and -4 mRNA become restricted to the mesenchyme and BMP5 and -7 mRNA to the myocardium. At the venous pole, BMP2, -5, and -7 mRNA are expressed in the distal myocardial border of the caval vein, while BMP2, -5, -6, and -7 mRNA are expressed in the distal myocardium around the pulmonary vein. BMP4 mRNA is expressed in the adjacent mesenchyme at both sides. During muscularization of the atrioventricular cushions and the tricuspid valve, the cardiomyocytes that protrude into the mesenchyme express BMP2, -4, -5, and -7 mRNA, whereas BMP6 mRNA is expressed in the cushion mesenchyme. The myocardial protrusions formed in the mesenchymal proximal outlet septum express BMP4, -5, and -7 mRNA, while BMP2 and -6 mRNA are expressed in the mesenchyme. The spatiotemporal expression patterns of these BMPs in relation to myocardium formation at the distal ends and within the heart suggest a role for BMPs in myocardium formation. During delamination of the valves, BMP4 and -6 mRNA are expressed at the ventricular side of the forming mitral valve, BMP4 mRNA at the ventricular side of the forming tricuspid valve, and BMP2, -4, and -6 mRNA at the vascular side of the forming semilunar valves. 相似文献
33.
Peritoneal fluid concentrations of interleukin-8 in women with endometriosis: relationship to stage of disease 总被引:7,自引:10,他引:7
Gazvani MR; Christmas S; Quenby S; Kirwan J; Johnson PM; Kingsland CR 《Human reproduction (Oxford, England)》1998,13(7):1957-1961
There is increasing evidence that immunological mechanisms play a role in
the pathogenesis and pathophysiology of endometriosis. It was therefore of
interest to study interleukin-8 (IL-8), a chemokine, in the peritoneal
fluid and peripheral blood of women undergoing laparoscopic procedures. The
presence and concentrations of IL-8 in relation to endometriosis,
infertility and abdominal pain were evaluated. Samples of peritoneal fluid
(n = 49) and peripheral blood (n = 50) were obtained from 50 consecutive
patients undergoing laparoscopic surgery for various gynaecological
indications (abdominal pain, infertility, sterilization). IL-8 was present
in the peritoneal fluid of most women (87%). The concentration of IL-8 in
the peritoneal fluid was higher in women with endometriosis compared to
women without (P = 0.02). This difference was more pronounced in early
(stage 1) endometriosis (P = 0.001). IL-8 concentrations in the peritoneal
fluid were also higher in women with early endometriosis compared to women
with later stages of the disease (P = 0.003). Peripheral blood
concentrations did not correlate with peritoneal fluid concentrations of
IL-8 and/or the presence of endometriosis. We conclude that IL-8 is an
important factor that may contribute to the pathogenesis of endometriosis
possibly by promoting neovascularization. This information can be a guide
in the development of new therapeutic approaches for the treatment of
endometriosis.
相似文献
34.
35.
Recessively inherited L-DOPA-responsive parkinsonism in infancy caused by a point mutation (L205P) in the tyrosine hydroxylase gene 总被引:4,自引:0,他引:4
36.
We had previously used an electrophoretic transfer procedure to determine the topographic distribution of low density lipoprotein (LDL) accumulation in the aortic intima of normolipemic swine. In this present study we have employed a similar procedure to assess whether LDL-rich sites consistently demonstrate increased intimal thickening at the iliac bifurcation and common iliac arteries. The topographic distribution of LDL-rich sites was determined in the aortas of six subjects ranging in age from 16 to 36 years, by transferring LDL by electrophoresis from the tissue into an agarose gel containing anti-LDL, and then staining the immunofixed LDL in the gel for lipid. LDL-rich sites were found in all but two of these cases. On the basis of control studies establishing the level of nonspecific staining, we determined that the cutoff between LDL-rich and LDL-poor zones was 37 mg apoB protein/mm2 intimal surface area. Intimal thickening was found to be threefold greater in LDL-rich than in LDL-poor regions. These results confirm and extend earlier immunohistochemical studies suggesting a preferential accumulation of LDL at sites of intimal thickening in human arteries. 相似文献
37.
Psychological distress in high-risk youth with asthma 总被引:5,自引:0,他引:5
Gillaspy SR Hoff AL Mullins LL Van Pelt JC Chaney JM 《Journal of pediatric psychology》2002,27(4):363-371
OBJECTIVE: To examine the relationship between asthma and psychological distress among adolescents already at-risk for adjustment problems secondary to lower economic strata and educational or vocational failure. METHOD: Twenty-five high-risk adolescents with asthma and 25 high-risk controls without asthma 16 to 21 years old completed the Brief Symptom Inventory, the Beck Depression Inventory, and the Beck Anxiety Inventory. RESULTS: Adolescents with asthma had significantly higher scores on multiple measures of psychological distress. Specifically, adolescents with asthma evidenced higher levels of anxiety, depression, and global psychological distress than those without asthma. CONCLUSIONS: High-risk adolescents with asthma may be more likely to experience psychological distress than those without asthma. Our findings suggest that asthma constitutes an additional significant independent stressor or risk factor among adolescents who already are at high risk for multiple adjustment problems. 相似文献
38.
Distinguishing characteristics of a new neuroblastoma cell line 总被引:3,自引:0,他引:3
J T Casper J M Trent J Harb V Piaskowski M Helmsworth J Finlan D D Von Hoff 《Cancer Genetics and Cytogenetics》1983,10(2):177-186
The characteristics of a new neuroblastoma cell line (MC-NB-1) established from the bone marrow of a 2-year-old male are described. Morphologically, the cells appear as flattened and epithelial-like or as small and spherical. Electron microscopy demonstrated microtubules and dense core secretory granules. The doubling time was approximately 35 hr. Isoenzyme patterns and catecholamine secretion indicated a human line of neuronal origin. The soft agar tumor colony forming system demonstrated drug resistance in vitro comparable to in vivo nonresponsiveness. The stemline karyotype of MC-NB-1 is 44,Y,del(1) (p22:), -4, -7, +del(7)(q22:), -16, +t(7;16)(16pter leads to 16q24::7q22 leads to 7q32), -17. Additionally, double-minute bodies were observed. However, no evidence of homogeneous staining regions (HSRs) were detected. 相似文献
39.
DL?MagerEmail author AD?Haffajee PM?Devlin CM?Norris MR?Posner JM?Goodson 《Journal of translational medicine》2005,3(1):27
Background
The purpose of the present investigation was to determine if the salivary counts of 40 common oral bacteria in subjects with an oral squamous cell carcinoma (OSCC) lesion would differ from those found in cancer-free (OSCC-free) controls. 相似文献40.
Transforming growth factor-beta3-loaded microtextured membranes for skin regeneration in dermal wounds 总被引:1,自引:0,他引:1
Vooijs DP Walboomers XF Parker JA Von den Hoff JW Jansen JA 《Journal of biomedical materials research. Part A》2004,70(3):402-411
Adverse effects of wound healing, such as excessive scar tissue formation, wound contraction, or nonhealing wounds represent a major clinical issue in today's healthcare. Transforming growth factor (TGF)-beta3 has specifically been implicated in wound healing. Our hypothesis was that local administration of TGF-beta3 to excisional dermal wounds would diminish wound contraction and scar formation. Microtextured wound covers, containing different concentrations of TGF-beta3, were placed onto full-thickness excisional skin wounds in guinea pigs. Tattooed reference marks were used to quantify wound contraction. Sixty-four male guinea pigs in four study groups (5 ng TGF-beta3, 50 ng TGF-beta3, no growth factor, sham wound) were followed for up to 6 weeks. We analyzed 19 different parameters of wound healing. Results showed that, in some instances, the 50-ng TGF-beta3 group gave less contraction, whereas the 5-ng TGF-beta3 group gave more contraction. These differences confirm that TGF-beta3 has an optimum working concentration, and suggest this concentration to be closer to 50 ng than to 5 ng TGF-beta3. However, only very few significant differences occurred, and thus we conclude that the clinical relevance of our findings is negligible. Earlier studies, reporting clinically improved wound healing by TGF-beta3, could therefore not be confirmed by this study. 相似文献