全文获取类型
收费全文 | 8677篇 |
免费 | 774篇 |
国内免费 | 46篇 |
专业分类
耳鼻咽喉 | 88篇 |
儿科学 | 376篇 |
妇产科学 | 143篇 |
基础医学 | 1128篇 |
口腔科学 | 245篇 |
临床医学 | 909篇 |
内科学 | 1975篇 |
皮肤病学 | 160篇 |
神经病学 | 729篇 |
特种医学 | 651篇 |
外国民族医学 | 2篇 |
外科学 | 1100篇 |
综合类 | 97篇 |
一般理论 | 1篇 |
预防医学 | 688篇 |
眼科学 | 144篇 |
药学 | 430篇 |
中国医学 | 16篇 |
肿瘤学 | 615篇 |
出版年
2023年 | 39篇 |
2022年 | 70篇 |
2021年 | 201篇 |
2020年 | 95篇 |
2019年 | 252篇 |
2018年 | 284篇 |
2017年 | 202篇 |
2016年 | 203篇 |
2015年 | 236篇 |
2014年 | 269篇 |
2013年 | 394篇 |
2012年 | 421篇 |
2011年 | 407篇 |
2010年 | 326篇 |
2009年 | 264篇 |
2008年 | 351篇 |
2007年 | 376篇 |
2006年 | 371篇 |
2005年 | 324篇 |
2004年 | 262篇 |
2003年 | 257篇 |
2002年 | 279篇 |
2001年 | 186篇 |
2000年 | 220篇 |
1999年 | 199篇 |
1998年 | 199篇 |
1997年 | 188篇 |
1996年 | 177篇 |
1995年 | 143篇 |
1994年 | 123篇 |
1993年 | 120篇 |
1992年 | 164篇 |
1991年 | 177篇 |
1990年 | 143篇 |
1989年 | 190篇 |
1988年 | 162篇 |
1987年 | 147篇 |
1986年 | 155篇 |
1985年 | 121篇 |
1984年 | 91篇 |
1983年 | 85篇 |
1982年 | 57篇 |
1981年 | 47篇 |
1980年 | 61篇 |
1979年 | 64篇 |
1978年 | 37篇 |
1977年 | 45篇 |
1976年 | 52篇 |
1975年 | 44篇 |
1973年 | 35篇 |
排序方式: 共有9497条查询结果,搜索用时 15 毫秒
31.
Alteration of the LRP1B gene region is associated with high grade of urothelial cancer 总被引:6,自引:0,他引:6
Langbein S Szakacs O Wilhelm M Sukosd F Weber S Jauch A Lopez Beltran A Alken P Kälble T Kovacs G 《Laboratory investigation; a journal of technical methods and pathology》2002,82(5):639-643
We have delineated regions of interest at chromosome 2q21.2, 2q36.3, and 2q37.1 by deletion mapping of 114 urothelial cancers (UC). Altogether, 17%, 18%, and 63% of the G1, G2, and G3 tumors displayed loss of heterozygosity at chromosome 2q, respectively, The region at 2q21.2 was narrowed down to the LRP1B gene (NT_005129.6). Hemi- and homozygous deletion at the LRP1B gene region was seen in 31 of 114 UCs. Only 8% of the UCs with G1 and none with G2 tumors showed loss of heterozygosity at the LRP1B gene, whereas 49% of the G3 UCs had allelic loss at this region. RT-PCR analysis of the LRP1B gene showed the lack of expression of several exons in 2 of 9 cases analyzed. Our analysis suggests that the LRP1B gene is a candidate tumor suppressor gene in UCs. 相似文献
32.
Cellular changes produced by viruses can be readily identified using light microscopy and Papanicolaou stain of a fixed specimen. These findings can then be confirmed by viral culture and/or electron microscopy studies. Human polyomavirus, common in transplant recipients or otherwise immunocompromised patients, is one virus that can be identified using these methods. The following is a case study of a 4-yr-old boy with no known immune impairment who exhibited human papovavirus (polyomavirus) on a routine urine examination. The diagnosis was confirmed by electron microscopy. 相似文献
33.
How to use Chlamydia antibody testing in subfertility patients 总被引:1,自引:9,他引:1
Screening for tubal factor subfertility by means of Chlamydia antibody
testing (CAT) was introduced into the initial work-up of subfertile couples
several years ago. The results reported, however, are heterogeneous, and no
uniformity exists in cut-off levels of titres, or in definitions of tubal
factor subfertility. We performed a prospective cohort study to evaluate
the implications of varying the definitions of tubal pathology and of
modifying the cut-off levels on the clinical impact of CAT in predicting
tubal factor subfertility. In 227 consecutive patients who attended our
fertility clinic, the Chlamydia IgG antibody titre was determined and
related to tuboperitoneal abnormalities at laparoscopy as a reference
standard. According to received operating characteristic (ROC) curve
analysis, a titre of 16 is the optimum cut-off level. Increasing the
cut-off level improves specificity and positive likelihood ratio (LR+), at
the expense of sensitivity and negative LR (LR-). Changing the definition
of tubal factor subfertility from unspecified tuboperitoneal abnormalities
into extensive adhesions and/or bilateral distal tubal occlusion improves
LR+, LR- and kappa significantly. We conclude that CAT is more accurate in
predicting severe distal tubal pathology than unspecified tuboperitoneal
abnormalities. Although from a statistical point of view a titre of 16 is
the optimum cut-off level, from a clinical point of view 32 or 64 may be
preferable, depending on the aim of screening and the inception cohort.
相似文献
34.
R. F. Maes A. Vieira I. Gomes P. Auge de Mello C. Bernal Lopez K. Costa Freitas 《Archives of virology》1977,55(4):275-285
Summary The effect of various polycations on the immune response potentiated with poly I:C was studied. It was found that low molecular weight polycations had no potentiating effect. Polylysine was ineffective whereas protamine was superior to lysozyme, poly-arginine, poly-histidine, DEAE-Dextran and histone.A foot-and-mouth disease trivalent vaccine composed of strains A24 Cruzeiro, O1 Caseros and C2 Resende elicited no immune response in swine when adjuvanted with aluminium hydroxide but was effective when emulsified in oil. In general, the immune response was potentiated ten-fold when the emulsion contained poly I:C. The antibody production was in most cases further potentiated by a factor of ten when the nucleic acid double-strand was complexed with 1:10 (w/w) DEAE-Dextran. Protamine was as effective, or perhaps even more, than DEAE-Dextran to this effect.Guinea pigs vaccinated with a water-in-oil emulsion type monovalent C3 vaccine showed an increase in antibody production when the vaccine contained poly I:C or poly I:C complexed with 1:10 (w/w) protamine.With 4 Figures 相似文献
35.
36.
37.
38.
39.
Ayuso R Lehrer SB Lopez M Reese G Ibañez MD Esteban MM Ownby DR Schwartz H 《Allergy》2000,55(4):348-354
BACKGROUND: Although beef is a main source of protein in Western diets, very little has been published on allergic reactions to beef or the main allergens implicated in these reactions. The aim was to evaluate the IgE antibody response to beef in suspected meat-allergic subjects and assess cross-reactivity of beef with other vertebrate meats. METHODS: Fifty-seven sera from suspected meat-allergic subjects were tested by grid blot for specific IgE antibodies to vertebrate meats (beef, lamb, pork, venison, and chicken), and the patterns of recognition of meat proteins were assessed by immunoblot studies. RESULTS: A 160-kDa band, identified as bovine IgG, was detected in raw beef in 83% (10/12) of beef-allergic subjects but in only 24% of the beef-tolerant subjects. IgE reactivity to a band of similar mol. mass was detected also in lamb and venison, but rarely in pork or chicken. Complete inhibition of the IgE reactivity to the bovine IgG was obtained with lamb, venison, and milk. IgE reactivity to this band also completely disappeared when beef or lamb extracts were separated under reducing conditions, indicating conformational epitopes. CONCLUSIONS: Bovine IgG appears to be a major cross-reacting meat allergen that could predict beef allergy. Further studies with oral IgG challenges should be performed to document the conclusion that in vitro reactivity correlates with clinical hypersensitivity. The role of bovine IgG in other bovine products such as milk, dander, or hair must also be studied, and the hypothesis that it is a cross-reacting allergen with other mammalian products validated. 相似文献
40.