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   924895篇
  免费   75986篇
  国内免费   1969篇
耳鼻咽喉   13609篇
儿科学   26450篇
妇产科学   26461篇
基础医学   132402篇
口腔科学   27029篇
临床医学   82313篇
内科学   176545篇
皮肤病学   17847篇
神经病学   76468篇
特种医学   37907篇
外国民族医学   175篇
外科学   144909篇
综合类   25724篇
现状与发展   2篇
一般理论   313篇
预防医学   73267篇
眼科学   22285篇
药学   68802篇
  2篇
中国医学   1676篇
肿瘤学   48664篇
  2018年   8192篇
  2015年   8672篇
  2014年   12456篇
  2013年   19056篇
  2012年   25729篇
  2011年   27079篇
  2010年   15672篇
  2009年   14761篇
  2008年   25528篇
  2007年   27995篇
  2006年   27808篇
  2005年   27355篇
  2004年   26759篇
  2003年   25768篇
  2002年   24957篇
  2001年   37238篇
  2000年   37857篇
  1999年   32244篇
  1998年   10032篇
  1997年   9253篇
  1996年   9140篇
  1995年   8640篇
  1994年   8288篇
  1992年   27706篇
  1991年   27169篇
  1990年   26596篇
  1989年   25705篇
  1988年   24088篇
  1987年   23851篇
  1986年   22645篇
  1985年   22011篇
  1984年   17235篇
  1983年   14737篇
  1982年   9543篇
  1981年   8842篇
  1980年   8327篇
  1979年   17489篇
  1978年   12725篇
  1977年   10738篇
  1976年   9854篇
  1975年   10631篇
  1974年   13224篇
  1973年   12660篇
  1972年   11989篇
  1971年   11054篇
  1970年   10524篇
  1969年   10206篇
  1968年   9152篇
  1967年   8478篇
  1966年   7895篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
The authors studied the cumulative probability of pregnancy for up to 4 consecutive embryo transfer (ET) cycles with ICSI performed for male factor. Transfers could be either fresh or frozen. The clinical pregnancy rate (PR) for the first 4 cycles were similar [44% (61/366); 31% (44/138); 45% (14/31); 44% (4/9)]. Delivery rates were also similar. There was a lower PR on the second retrieval vs. the first retrieval (47% vs. 29%), but this may be related to most of the second retrievals occurring in the second transfer cycle (67%, 31/55); this may be explained by women who were poor responders and required another retrieval without a frozen ET. The majority of transfers in cycle 1 were fresh, whereas cycles 2-4 used primarily frozen-thawed embryos. These data should be helpful for patients requiring IVF with ICSI in deciding to continue with more IVF cycles or consider other  相似文献   
62.
Summary To evaluate the potential effect of androgens on the development and growth of human colorectal adenomas, the prevalence and concentration of cytosolic androgen receptors (AR) were analysed in 26 adenomas and 19 samples of normal colonic mucosa by a hybrid ligand receptor-binding assay. AR were detected in 7 of the adenomas (26.9%), and in 6 of the normal mucosa samples (31.6%). In the adenomas, AR levels demonstrated were low, ranging from 6 to 31 fmol/mg cytosol protein, and dissociation constants (Kds) ranged from 0.17–2.7x10-9 M. Of 13 adenomas excised from men, 6 (46%) had positive receptor activity, whereas only 1 of 13 (7.7%) from women was positive (P=0.03, Fisher's exact test). There was no correlation between AR titre and patient age, or between adenoma size and histological type or degree of dysplasia. In normal mucosa, AR levels ranged from 7 to 33 fmol/mg and Kds ranges from 0.24–3.1x10-9 M. There was no significant difference between either AR prevalence or levels in the adenomas and normal mucosa. The sex difference was exclusive to the adenoma. Endogenous androgen may play a role in adenoma development early in the promotional process.  相似文献   
63.
64.
65.
Using indirect immunohistochemistry and an antiserum raised against rat corticotrophin-releasing factor (CRF) we have outlined an asymmetric network of cells and varicose fibers in sheep adrenal cortex. This network was not associated with the larger splanchnic nerves, but was occasionally found in small bundles or with blood vessels; in most instances fibers were found weaving independently through cortical parenchyma. A plexus of fibers was found in the zona reticularis, with a few fibers ramifying into adjacent medulla. Uni or bipolar cells were found throughout the cortex, with the greatest frequency at the corticomedullary junction; a multipolar-type cell was also found in this area. Staining of varicose structures and most cells was abolished by incubation with excess rat CRF 1-41, but not by ovine CRF or a range of other peptides. Though the immunoreactive species has not as yet been identified, it may thus share homology with sequences present in rat but not ovine CRF.  相似文献   
66.
An epidemiologic study of coeliac disease in a geographically defined area of Sweden showed that the prevalence was 95.5/10(5) inhabitants aged 15 years or more. The highest prevalence, 178/10(5) inhabitants, was found in the age group 65-74 years. The lowest prevalence, 39/10(5) inhabitants, was found in patients aged 15-24 years. Among the associated diseases an especially high incidence of associated thyroid disease was observed: thyrotoxicosis occurred in 5.0% and hypothyroidism in 5.8% of the patients.  相似文献   
67.
The use of additional epidural sympathetic block during and after microvascular surgery in the lower extremities to prevent vasospasm is generally agreed on. However, a significant fall in the perfusion rate of the transplants was seen after application of bupivacaine (Marcain) via the epidural catheter. This effect has, to our knowledge, not been described before and is probably caused by the sympathectomy effect of this type of analgesia.  相似文献   
68.
Median cervical cysts are congenital anomalies arising from remaining thyroglossal duct epithelium. A major problem in the surgical treatment of these cysts is the high frequency of recurrence. Embryonic considerations indicate an important causal role for the hyoid bone in these recurrences. We studied the relationship between operative techniques and the number of recurrences in 36 patients treated in our hospital. Fourteen patients sent from other hospitals had a recurrent fistula; in thirteen cases the hyoid bone was still in place. All patients who had the central part of the hyoid bone excised were cured. In 14 patients without adequate excisions of the hyoid bone we found four recurrences. To prevent recurrence a total excision of thyroglossal duct epithelium is necessary.  相似文献   
69.
70.
A murine monoclonal antibody PASE/4LJ to prostatic acid phosphatase (PAP) was used to immunostain a wide variety of sections of benign and malignant tissues (654 blocks). Non-neoplastic adult and fetal prostatic glands, primary and metastatic prostatic carcinomas, and scattered cells in prostatic and penile urethra were positive. Rat, dog and rabbit prostates were negative. Nine of 400 tumours of non-prostatic origin showed some positivity: 6/36 carcinoids, 1/9 islet cell tumours, 1/55 ovarian adenocarcinomas (serous) and one carcinosarcoma of the lung (epithelial portion). Positive staining was seen in islet cells in 4/5 specimens of normal pancreas, and in 4/9 blocks of normal pancreas surrounding a pancreatic tumour. Loops of Henle, maculae densae, and distal tubules in 10/10 fetal and 2/9 adult kidneys were also positive, with proximal tubules and collecting ducts negative. All other 159 blocks of non-neoplastic adult and fetal tissues were negative. The antibody was also affinity purified from ascitic fluid, and shown not to inhibit the enzyme activity of prostatic acid phosphatase.  相似文献   
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