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   1978篇
  免费   4篇
电工技术   2篇
化学工业   29篇
金属工艺   2篇
机械仪表   5篇
建筑科学   6篇
矿业工程   1篇
能源动力   4篇
轻工业   28篇
石油天然气   2篇
无线电   26篇
一般工业技术   33篇
冶金工业   1806篇
原子能技术   4篇
自动化技术   34篇
  2023年   3篇
  2020年   3篇
  2019年   2篇
  2018年   3篇
  2016年   2篇
  2015年   5篇
  2014年   3篇
  2013年   5篇
  2012年   9篇
  2011年   6篇
  2010年   4篇
  2009年   6篇
  2008年   10篇
  2007年   6篇
  2006年   3篇
  2005年   3篇
  2004年   4篇
  2003年   3篇
  2002年   6篇
  2001年   2篇
  2000年   10篇
  1999年   56篇
  1998年   516篇
  1997年   301篇
  1996年   203篇
  1995年   101篇
  1994年   96篇
  1993年   124篇
  1992年   21篇
  1991年   32篇
  1990年   32篇
  1989年   32篇
  1988年   44篇
  1987年   35篇
  1986年   29篇
  1985年   23篇
  1984年   2篇
  1983年   12篇
  1982年   14篇
  1981年   21篇
  1980年   12篇
  1978年   2篇
  1977年   52篇
  1976年   108篇
  1975年   3篇
  1967年   1篇
  1966年   1篇
  1963年   1篇
  1955年   1篇
  1927年   2篇
排序方式: 共有1982条查询结果,搜索用时 234 毫秒
91.
To observe the expression of p16, pRb, cdk4 and cyclinD1 in non-small cell lung cancers, 104 cases of resected lung cancers were collected, which included squamous cell carcinomas, adenocarcinomas and large cell carcinomas. Immunohistochemistry assay was carried out. The results showed that 67% of squamous cell carcinomas and 46% of adenocarcinomas expressed p16, 64% of squamous cell carcinomas and 85% of adenocarcinomas expressed pRb and 66% of cancers expressed p16 or pRb. About 70% of the tumors expressed cyclinD1. More than 90% of the tumors expressed cdk4 and there was an increased trend with decreasing differentiation of both squamous cell carcinomas and adenocarcinomas. Sixty-seven percent of the highly differentiated and 100% of the poorly differentiated squamous cell carcinomas expressed cdk4. The aberrant p16 and pRb gene product expression played a significant role in the development and histological subtype of lung cancers by conditioning the biological behavior of NSCLC. cdk4 was an important factor in histological differentiation.  相似文献   
92.
93.
Blood-gas tensions, FRC and volume of trapped gas (VTG) in the lung were measured in patients on the day before lower abdominal gynaecological surgery, and twice on the day following surgery, before and after establishing lumbar extradural block (EDB) using 0.5% bupivacaine to provide analgesia after operation. FRC and VTG were measured with the closed-circuit helium-dilution technique. Mean VTG was 175 ml before operation and 275 ml after operation. PaO2 decreased significantly after operation, and the changes in FRC and VTG that occurred were related qualitatively. EDB did not significantly alter FRC, VTG or PaO2. Individual changes in FRC could not be related to changes in VTG or PaO2. Although EDB provided effective analgesia, the variables measured did not indicate that EDB conferred an immediate respiratory advantage.  相似文献   
94.
Ninety-two patients with Dukes' class C colonic carcinoma, divided equally into those who survived 5 years or more and those surviving less than 5 years after resection for cure, underwent evaluation of multiple histopathologic characteristics of the primary tumor and the uninvolved regional lymph nodes. These characteristics were analyzed by the chi-square test for correlation with survival. A statistically significant correlation (P less than 0.05) in the group who survived 5 years or more was observed for Broders' grades 1 and 2, tumor not involving serosa, and a pushing tumor margin. Of the 14 patients who had a pushing tumor margin and tumor not involving serosa, 12 (86%) survived 5 years or more. Seven patients had an infiltrating tumor margin and peritumor venous invasion, and of this group, only one (14%) survived 5 years or more. Histopathologic characteristics of host immune reaction at the tumor or in the uninvolved regional lymph nodes did not correlate with survival.  相似文献   
95.
On the internal or parietal surface of the left ventricle in man and in mammals are two papillary muscles, which are almost identical and well developed. In man, these muscles are known as the m. papillaris parietalis anterior sinister and the m. papillaris parietalis posterior dexter, in mammals, the m. papillaris parietalis cranialis sinister and caudalis dexter, or, in shorter form, mm. papillaris parietalis sinister et dexter. In the right ventricle in man, there are two papillary parietal muscles: the mm. papillares anteriores et posteriores. On the septum of this ventricle there is, as in mammals, a muscle called the m. papillaris septalis medialis seu subarteriosus. Beside it are one or several smaller muscles, varying from one individual to another: the mm. papillares septales accessorii seu parvi. In the right ventricle of the mammalian heart is found, in addition to the m. parietalis septalis subarteriosus, already mentioned, a m. papillaris caudalis, more or less well developed in some species and, in the majority of mammals, the m. papillaris septalis cranials, which is always well developed. In certain mammals, there is, in rare cases, a m. papillaris septomarginalis seu parietalis. It may be said, in conclusion, that, in a large number of mammals, there is, on the internal surface of the external wall of the right ventricle, a reasonably well developed m. papillaris parietalis.  相似文献   
96.
If a spinal root of a baboon or rhesus monkey is trapped in an initially loose-fitting silicone rubber channel containing two or more platinum electrodes, electrical pulses sent through these electrodes can stimulate nerve fibres close to the cathode and block the resulting impulses close to the anode. We show (1) how anodal break excitation and excitation of fibres outside the silicone rubber channel can be avoided; (2) that an implant 26 months old behaves like a recent one; (3) that in a root containing somatic motor fibres and parasympathetic fibres, all somatic motor fibres can be blocked and most or all parasympathetic fibres excited but not blocked; (4) that provided that the electrodes pass no net direct current, prolonged stimulation with block can be harmless; (5) how block can be achieved in one direction only along a root; (6) that a peripheral nerve can be blocked by the same techniques.  相似文献   
97.
A survey questionnaire eliciting information on the number of internships offered, average salary of interns, selection criteria, and percentages of work time was sent to 294 American Psychological Association (APA)- and non-APA-approved internship sites. Results of this study and the new criteria for accreditation indicate that students from approved doctoral programs have a definite advantage in the internship marketplace. Sufficient evidence exists, however, to conclude that students from non-APA-approved programs may be encouraged to risk competing for APA-approved internships. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
98.
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