首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   21486篇
  免费   1283篇
  国内免费   71篇
耳鼻咽喉   332篇
儿科学   1219篇
妇产科学   507篇
基础医学   1857篇
口腔科学   392篇
临床医学   1772篇
内科学   5129篇
皮肤病学   342篇
神经病学   1052篇
特种医学   934篇
外科学   3751篇
综合类   486篇
一般理论   3篇
预防医学   1128篇
眼科学   911篇
药学   1576篇
  2篇
中国医学   71篇
肿瘤学   1376篇
  2023年   164篇
  2022年   344篇
  2021年   761篇
  2020年   409篇
  2019年   611篇
  2018年   714篇
  2017年   499篇
  2016年   504篇
  2015年   522篇
  2014年   802篇
  2013年   1006篇
  2012年   1504篇
  2011年   1362篇
  2010年   885篇
  2009年   708篇
  2008年   1020篇
  2007年   1024篇
  2006年   955篇
  2005年   895篇
  2004年   801篇
  2003年   685篇
  2002年   618篇
  2001年   492篇
  2000年   520篇
  1999年   422篇
  1998年   244篇
  1997年   222篇
  1996年   206篇
  1995年   174篇
  1994年   155篇
  1993年   127篇
  1992年   299篇
  1991年   271篇
  1990年   230篇
  1989年   247篇
  1988年   202篇
  1987年   213篇
  1986年   173篇
  1985年   198篇
  1984年   168篇
  1983年   160篇
  1982年   81篇
  1981年   92篇
  1979年   120篇
  1978年   92篇
  1977年   71篇
  1974年   75篇
  1973年   111篇
  1972年   101篇
  1971年   70篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
This report documents the outcome of 25 pregnancies with elevated serum alpha-fetoprotein levels on two separate samplings despite normal anatomic appearance of the fetus on a detailed "consultative" sonographic examination. Six of these also had elevated amniotic fluid alpha-fetoprotein. All fetuses in this series were anatomically normal at time of delivery; one aborted fetus was triploid. Of the 25 pregnancies, 16 had sonographically demonstrable placental hemorrhage, eight retroplacental and eight subchorionic. One had hydropic changes in the placenta associated with triploidy. Of the subgroup of six pregnancies in which both serum and amniotic fluid values were elevated, one had a retroplacental hemorrhage, one had a subchorionic hemorrhage, and one had diffuse hydropic changes in the placenta. A control group of 112 patients with normal alpha-fetoprotein levels yielded four with small (less than 2 cm3) subchorionic hemorrhage. The occurrence rate of placental hemorrhage in women with elevated alpha-fetoprotein and normal fetus was 64%, whereas the control group of patients with normal alpha-fetoprotein had a 3.6% occurrence rate of placental hemorrhage. Sonographically detectable placental abnormalities may be associated with elevated alpha-fetoprotein in serum and/or amniotic fluid samples. Such abnormalities may occur because of fetomaternal admixture associated with placental hemorrhage and/or intraamniotic bleeding resulting from subchorionic hemorrhage.  相似文献   
93.
In an unusual nosocomial outbreak, 13 staff and 11 patients in an acute and chronic health care facility were infected with the zoophilic dermatophyte, Microsporum canis. The dermatophyte was apparently introduced into the facility by a single infected patient. Likely modes of subsequent disease transmission include person-to-person contact, handling of contaminated laundry, and use of a shared razor. Infection control measures for managing such outbreaks are discussed.  相似文献   
94.

29. Tagung der ?sterreichischen Gesellschaft für Chirurgie und Ihrer Assoziierten Fachgesellschaften Innsbruck, 2. bis 4. Juni 1988 Herausgeber: E. Bodner und G. Szinicz Abstracts

Der chirurgische Part im Rahmen multimodaler Therapiekonzepte in der Onkologie-Schilddrüse  相似文献   
95.
A tissue culture procedure has been developed for the rapid multiplication of VALERIANA WALLICHII D C. through shoot tip and axillary bud explants. MS medium containing Kn or BAP (5.0 mg/l (-1)) in combination with IAA (1.0 mg/l (-1)) induced an optimal growth of shoots within 6-8 days from both apical and axillary bud explants. The roots developed on the same medium within 2-3 weeks. Hardening of IN VITRO grown plantlets in pots under glass-house conditions was dependent upon the temperature and humidity. A cold-temperate climate favoured early establishment. Following the given procedure, a large number of plants have been established under field conditions at two locations. The method has implications in the early introduction of an elite population as well as its improvement.  相似文献   
96.
97.
Localization of a gene for otosclerosis to chromosome 15q25-q26   总被引:5,自引:0,他引:5  
Among white adults otosclerosis is the single most common cause of hearing impairment. Although the genetics of this disease are controversial, the majority of studies indicate autosomal dominant inheritance with reduced penetrance. We studied a large multi- generational family in which otosclerosis has been inherited in an autosomal dominant pattern. Five of16 affected persons have surgically confirmed otosclerosis; the remaining nine have a conductive hearing loss but have not undergone corrective surgery. To locate the disease- causing gene we completed genetic linkage analysis using short tandem repeat polymorphisms (STRPs) distributed over the entire genome. Multipoint linkage analysis showed that only one genomic region, on chromosome 15q, generated a lod score >2.0. Additional STRPs were typed in this area, resulting in a lod score of 3.4. STRPs FES (centromeric) and D15S657 (telomeric) flank the 14. 5 cM region that contains an otosclerosis gene.   相似文献   
98.
X-linked liver glycogenosis type II (XLG II) is a recently described X- linked liver glycogen storage disease, mainly characterized by enlarged liver and growth retardation. These clinical symptoms are very similar to those of XLG I. In contrast to XLG I patients, however, XLG II patients do not show an in vitro enzymatic deficiency of phosphorylase kinase (PHK). Recently, mutations were identified in the gene encoding the liver alpha subunit of PHK (PHKA2) in XLG I patients. We have now studied the PHKA2 gene of four unrelated XLG II patients and identified four different mutations in the open reading frame, including a deletion of three nucleotides, an insertion of six nucleotides and two missense mutations. These results indicate that XLG II is due to mutations in PHKA2. In contrast to XLG I, XLG II is caused by mutations that lead to minor structural abnormalities in the primary structure of the liver alpha subunit of PHK. These mutations are found in a conserved RXX(X)T motif, resembling known phosphorylation sites that might be involved in the regulation of PHK. These findings might explain why the in vitro PHK enzymatic activity is not deficient in XLG II, whereas it is in XLG I.   相似文献   
99.
100.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号