全文获取类型
收费全文 | 33258篇 |
免费 | 1742篇 |
国内免费 | 162篇 |
专业分类
耳鼻咽喉 | 298篇 |
儿科学 | 494篇 |
妇产科学 | 373篇 |
基础医学 | 4450篇 |
口腔科学 | 1034篇 |
临床医学 | 2162篇 |
内科学 | 7884篇 |
皮肤病学 | 867篇 |
神经病学 | 2337篇 |
特种医学 | 1279篇 |
外科学 | 5684篇 |
综合类 | 161篇 |
一般理论 | 1篇 |
预防医学 | 1020篇 |
眼科学 | 766篇 |
药学 | 2553篇 |
中国医学 | 49篇 |
肿瘤学 | 3750篇 |
出版年
2023年 | 146篇 |
2022年 | 326篇 |
2021年 | 564篇 |
2020年 | 334篇 |
2019年 | 413篇 |
2018年 | 534篇 |
2017年 | 490篇 |
2016年 | 518篇 |
2015年 | 563篇 |
2014年 | 749篇 |
2013年 | 968篇 |
2012年 | 1418篇 |
2011年 | 1569篇 |
2010年 | 901篇 |
2009年 | 837篇 |
2008年 | 1395篇 |
2007年 | 1416篇 |
2006年 | 1443篇 |
2005年 | 1508篇 |
2004年 | 1414篇 |
2003年 | 1429篇 |
2002年 | 1357篇 |
2001年 | 1306篇 |
2000年 | 1341篇 |
1999年 | 1212篇 |
1998年 | 425篇 |
1997年 | 368篇 |
1996年 | 332篇 |
1995年 | 301篇 |
1994年 | 265篇 |
1993年 | 260篇 |
1992年 | 840篇 |
1991年 | 735篇 |
1990年 | 743篇 |
1989年 | 714篇 |
1988年 | 724篇 |
1987年 | 633篇 |
1986年 | 627篇 |
1985年 | 607篇 |
1984年 | 396篇 |
1983年 | 331篇 |
1982年 | 156篇 |
1979年 | 321篇 |
1978年 | 207篇 |
1977年 | 151篇 |
1975年 | 151篇 |
1974年 | 214篇 |
1973年 | 152篇 |
1972年 | 166篇 |
1971年 | 147篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
H Kimura Y Yamaguchi M Fujino N Yamamoto 《[Zasshi] [Journal]. Nihon Kyōbu Geka Gakkai》1992,40(8):1177-1181
Lymph node metastasis was analyzed quantitatively with 4 categories and relation to post surgical survival and recurrence pattern was studied in patients with pN2 primary lung cancer who underwent relatively curative or relatively noncurative resection of the tumors. There was no relation between metastatic coefficient and post surgical survival, however, better survival was observed when the metastatic ratio and metastatic frequency were low and metastatic mode was random or skip pattern rather than sequential pattern. Metastatic coefficient and metastatic frequency were higher in cases with recurrence in lymph nodes but the former was lower and the latter was higher in cases with recurrence in intra-pulmonary dissemination or metastasis. There was no relation between metastatic coefficient and distant metastasis but metastatic frequency was lower in cases with recurrence in distant metastasis. Cases with sequential lymph node metastasis showed a tendency of lymph node recurrence and intrapulmonary metastasis and those with random or skip metastasis of lymph nodes had a tendency of distant metastasis. 相似文献
92.
Peritumoral brain edema associated with meningioma--histological study of the tumor margin and surrounding brain. 总被引:2,自引:0,他引:2
Thirty-nine cases of intracranial meningiomas were analyzed to identify factors causing brain edema. Edema was significantly correlated with tumor size and the destruction of the leptomeninges and cortex. Meningotheliomatous meningioma tended to have more peritumoral edema. There was no correlation between the presence of edema and location of the tumor or histological features including lymphocytic infiltration and the presence of glial fibrillary acidic protein-positive cells in the tumor tissue. Larger tumors destroy the leptomeninges and cerebral cortex, allowing direct transmission of humoral edema-promoting factor or edema fluid into the white matter, resulting in vasogenic edema. 相似文献
93.
Mechanisms of long-lasting effects of benidipine on Ca current in guinea-pig ventricular cells. 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《British journal of pharmacology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
1. Benidipine (KW-3049), a new derivative of 1,4-dihydropyridine (DHP), showed dose-dependent inhibition of Ca current (ICa) which was elicited by depolarization from -40 mV to +10 mV at 0.2 Hz in single cardiac cells isolated from guinea-pig ventricle under whole cell voltage clamp. Half inhibition doses (IC50) of benidipine and nifedipine for the peak ICa at +10 mV were 2.7 nM and 63.1 nM, respectively. 2. A change in holding potential from -40 to -75 mV partially removed the block induced by both 10 nM benidipine and 100 nM nifedipine. The block of ICa by benidipine strongly depended upon holding potentials as did that induced by nifedipine. 3. The effect of 100 nM nifedipine was mostly removed when the cells were kept quiescent at holding potentials negative to -75 mV for 5 min after withdrawal of nifedipine. In contrast, hyperpolarization for several minutes did not significantly accelerate the removal of benidipine-induced block after withdrawal of the drug. Effects of 10 nM benidipine could not be washed out for up to 30 min regardless of the holding potentials. 4. It is suggested that the dissociation of benidipine from the DHP binding site, like that of nifedipine, is greatly accelerated by hyperpolarization. Benidipine but not nifedipine may have an additional interaction with the channel or lipid membrane and cannot be washed away even after the dissociation. Alternatively, the dissociation of benidipine from the DHP binding site may be too slow to occur substantially during the limited period of hyperpolarization in the present study (less than 30 min).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
94.
95.
T Yazu T Kimura K Yamamoto T Sumii Y Arita S Takano M Furukawa M Tanaka K Konomi H Nawata 《Pancreas》1992,7(4):503-506
A 72-year-old man with recurrent pancreatitis and a horseshoe-shaped anomaly of the pancreas is described. The diagnosis was made by endoscopic retrograde cholangiopancreatography (ERCP) and computed tomography scan; laparotomy was confirmatory. The abnormal duct branched to the lower left from an enlarged Santorini's duct; a thin Wirsung's duct was joined at its distal portion to the junction of the abnormal duct. The anomaly was associated with a cystic dilatation of the common bile duct with stone and cholecystolithiasis. This anomaly is considered to be a variation of the dominant dorsal duct syndrome. 相似文献
96.
97.
98.
Secretion in yeast of human lysozymes with different specific activities created by replacing valine-110 with proline by site-directed mutagenesis. 总被引:1,自引:1,他引:0
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
M Kikuchi Y Yamamoto Y Taniyama K Ishimaru W Yoshikawa Y Kaisho M Ikehara 《Proceedings of the National Academy of Sciences of the United States of America》1988,85(24):9411-9415
Computer graphics indicate that a steric hindrance exists between valine-110 side chain of human lysozyme (EC 3.2.1.17) and an acetyl group of a modified substrate that contains N6,O-diacetylmuramic acid. To alter the substrate specificity of human lysozyme to be effective on the modified substrate, we replaced the valine-110 residue with various amino acids by site-directed mutagenesis. One of the mutant proteins (valine residue replaced with proline:P110) was secreted in Saccharomyces cerevisiae as at least four components (P110-A, P110-B, P110-C, and P110-D) with different specific activities. Two components, P110-B and P110-D, were isolated in a pure form and structurally characterized. The results suggest that this mutation lowered the lytic activity against Micrococcus lysodeikticus by changing a local conformation of the catalytic site while keeping almost the same substrate binding sites. Our results also indicate that cis/trans isomerization of prolyl peptide bonds probably occurs in vivo and that the conformational change of protein as well as point mutations in genes might influence the molecular evolution of the protein. 相似文献
99.
T Hayashi M Ozaki I Mori M Saito T Itoh H Yamamoto 《International journal of experimental pathology》1992,73(2):173-181
The lactic dehydrogenase (LDH) level in plasma and the clearance of LDH in C.B-17 scid (severe combined immunodeficiency; SCID) mice were compared with those in C.B-17 or BALB/cCrSlc mice with or without lactic dehydrogenase virus (LDV) infection. The resting enzyme level in SCID mice showed little difference from that in C.B-17 or BALB/cCrSlc mice. The degree of increased plasma LDH level in SCID mice was lower than that in C.B-17 and BALB/cCrSlc mice after LDV infection. To assess the mechanisms of decrease in LDH elevation in SCID mice infected with LDV, virus replication was compared in SCID and BALB/cCrSlc mice. The infectivity titre of plasma in SCID mice was higher (more than 10 times) than that in BALB/cCrSlc mice. Moreover, the percentage of virus antigen positive Kupffer cells was higher in SCID mice than that in BALB/cCrSlc mice. The level of endogenous LDH release as a result of carbon tetrachloride treatment was similar in the SCID and BALB/cCrSlc mice. The clearance rate of endogenous LDH was greater in SCID mice than in BALB/cCrSlc mice with or without LDV infection. The rate of clearance of intravenously injected porcine LDH-5, but not porcine LDH-1, was enhanced in SCID mice as compared with that in BALB/cCrSlc mice. Furthermore, carbon clearance was higher in SCID mice than that in BALB/cCrSlc mice. These results suggest that the smaller increase of plasma LDH after infection might be due, at least in part, to the enhanced LDH-5 clearance function by macrophages in SCID mice. 相似文献
100.
H Naruse M Morita J Yamamoto H Kawamoto M Itano N Fukutake M Ohyanagi K Fujitani T Iwasaki M Fukuchi 《Journal of cardiology》1992,22(2-3):295-305
To evaluate the extent and characteristics of infarct areas, we performed indium-111 monoclonal antimyosin Fab (InAM), thallium-201 (TL) and Tc-99m pyrophosphate (PYP) imagings in 17 patients with acute myocardial infarction, and tried to find out the mechanism that causes difference of these imagings. In each study, the extent scores as an index of the infarct area were obtained by single photon emission computed tomography (SPECT), and comparisons were made between the results obtained. The overlap between InAM and TL imagings obtained by SPECT was evaluated. Location, severity, extent and patterns of accumulation were compared between InAM and PYP with both planar image and SPECT. The extent scores of InAM correlated well with those of TL (r = 0.73, p < 0.01). However, the overlap of both methods was recognized in 8 of 17 patients, in whom wall thickness of the infarct area as obtained by echocardiography was well preserved. The left ventricular regional asynergy was mild in 6 of these 8 patients. Coronary angiography showed poor or no collateral circulation in these cases. Although there were generally close correlations of the extent scores between InAM and PYP, discrepancy was noted in 2 cases for location; 2 for severity, 5 for extent, and 3 for patterns of accumulation. These differences may be attributed to the timings of imaging, coronary reperfusion and different mechanisms of accumulation. In conclusion, the extent of acute myocardial infarction obtained by InAM correlates well with those obtained by TL and PYP, with some exceptions. 相似文献