全文获取类型
收费全文 | 330307篇 |
免费 | 39613篇 |
国内免费 | 230篇 |
专业分类
370150篇 |
出版年
2016年 | 3641篇 |
2015年 | 5598篇 |
2014年 | 6368篇 |
2013年 | 8864篇 |
2012年 | 10179篇 |
2011年 | 10221篇 |
2010年 | 6951篇 |
2009年 | 6591篇 |
2008年 | 9288篇 |
2007年 | 9524篇 |
2006年 | 9136篇 |
2005年 | 9049篇 |
2004年 | 8818篇 |
2003年 | 8853篇 |
2002年 | 8547篇 |
2001年 | 11558篇 |
2000年 | 11589篇 |
1999年 | 9740篇 |
1998年 | 4183篇 |
1997年 | 4183篇 |
1996年 | 4130篇 |
1995年 | 3857篇 |
1994年 | 3853篇 |
1993年 | 3805篇 |
1992年 | 8527篇 |
1991年 | 8280篇 |
1990年 | 8131篇 |
1989年 | 7949篇 |
1988年 | 7555篇 |
1987年 | 7501篇 |
1986年 | 6941篇 |
1985年 | 7129篇 |
1984年 | 6071篇 |
1983年 | 5451篇 |
1982年 | 4499篇 |
1981年 | 4348篇 |
1980年 | 3966篇 |
1979年 | 6200篇 |
1978年 | 4930篇 |
1977年 | 4706篇 |
1976年 | 4496篇 |
1975年 | 4770篇 |
1974年 | 5285篇 |
1973年 | 5191篇 |
1972年 | 4755篇 |
1971年 | 4272篇 |
1970年 | 3794篇 |
1969年 | 3777篇 |
1968年 | 3367篇 |
1967年 | 2919篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
141.
W W Johnston 《Acta cytologica》1984,28(3):218-224
From the time of its introduction, in 1973, through November 1983, fine needle aspiration biopsy ( FNAB ) of the lung was used in the diagnostic evaluation of 1,015 patients at the Duke University Medical Center and Durham Veterans Administration Medical Center. A diagnosis of a primary lung cancer was established in 49.4% of the cases and malignant neoplasm metastatic to the lung in 14.1%; a benign diagnosis was made in 31.1% and an inconclusive one in 5.4%. In 123 patients in whom lung tissue was also available, cancer was correctly diagnosed by FNAB in 83.8%, not diagnosed by FNAB in 14.6% and incorrectly diagnosed in 1.6%. In 37 patients without cancer, FNAB detected an infectious organism or a specific morphologic type of inflammation (abscess and granuloma). 相似文献
142.
143.
The l-thyroxine binding site in human serum thyroxine-binding globulin was investigated by affinity labeling with N-bromoacetyl-l-thyroxine (BrAcT4). Competitive binding studies showed that, in the presence of 100 molar excess of BrAcT4, binding of thyroxine to thyroxine-binding globulin was nearly totally abolished. The reaction of BrAcT4 to form covalent binding was inhibited in the presence of thyroxine and the affinity-labeled thyroxinebinding globulin lost its ability to bind thyroxine. These results indicate BrAcT4 and thyroxine competed for the same binding site. Affinity labeling with 2 mol of BrAcT4/mol of thyroxine-binding globulin resulted in the covalent attachment of 0.7 mol of ligand. By amino acid analysis and high voltage paper electrophoresis, methionine was identified as the major residue labeled (75%). Lysine, tyrosine, and histidine were also found to be labeled to the extent of 8, 8, and 5%, respectively. 相似文献
144.
145.
W Van Beaumont 《Journal of applied physiology》1973,35(1):47-50
146.
147.
148.
149.
A total dosage up to 1 mg PGF2a as i.v. infusions of 10–40 μg/min. was investigated on patients with arrhythmias of several kinds. We found therapeutic effects in 5 of 6 patients with constant extrasystoles and in one patient with digitalis - induced partial AV-block respectively. In 3 of 4 patients with acute tachyarrhythmias the results were not convincing, probably due to a dosage not high enough. An increase of the diastolic stimulation threshold usually seen with other antiarrhythmics was not to be observed in 3 patients. The mechanism of action of PGF2a has not yet been clarified. 相似文献
150.