全文获取类型
收费全文 | 55953篇 |
免费 | 3295篇 |
国内免费 | 598篇 |
专业分类
耳鼻咽喉 | 985篇 |
儿科学 | 630篇 |
妇产科学 | 825篇 |
基础医学 | 9754篇 |
口腔科学 | 1352篇 |
临床医学 | 4885篇 |
内科学 | 10543篇 |
皮肤病学 | 1870篇 |
神经病学 | 3981篇 |
特种医学 | 2968篇 |
外科学 | 7471篇 |
综合类 | 213篇 |
现状与发展 | 1篇 |
一般理论 | 17篇 |
预防医学 | 2711篇 |
眼科学 | 1230篇 |
药学 | 4983篇 |
中国医学 | 624篇 |
肿瘤学 | 4803篇 |
出版年
2023年 | 428篇 |
2022年 | 1326篇 |
2021年 | 2056篇 |
2020年 | 985篇 |
2019年 | 1288篇 |
2018年 | 1665篇 |
2017年 | 1240篇 |
2016年 | 1757篇 |
2015年 | 2559篇 |
2014年 | 3058篇 |
2013年 | 3487篇 |
2012年 | 5312篇 |
2011年 | 4806篇 |
2010年 | 2802篇 |
2009年 | 2360篇 |
2008年 | 3415篇 |
2007年 | 3093篇 |
2006年 | 2652篇 |
2005年 | 2352篇 |
2004年 | 2023篇 |
2003年 | 1692篇 |
2002年 | 1435篇 |
2001年 | 1363篇 |
2000年 | 1262篇 |
1999年 | 906篇 |
1998年 | 362篇 |
1997年 | 250篇 |
1996年 | 208篇 |
1995年 | 176篇 |
1994年 | 148篇 |
1993年 | 132篇 |
1992年 | 332篇 |
1991年 | 316篇 |
1990年 | 280篇 |
1989年 | 258篇 |
1988年 | 247篇 |
1987年 | 248篇 |
1986年 | 177篇 |
1985年 | 165篇 |
1984年 | 119篇 |
1983年 | 111篇 |
1982年 | 55篇 |
1981年 | 58篇 |
1979年 | 81篇 |
1978年 | 68篇 |
1975年 | 50篇 |
1974年 | 60篇 |
1973年 | 51篇 |
1972年 | 50篇 |
1970年 | 49篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
To elucidate the mechanisms by which thiamine deficiency affects hepatic microsomal monooxygenase activities, the effect of thiamine deficiency on two constitutive cytochrome P450 isozymes, P450IIE1 and P450IIC11, was investigated, using weanling male Sprague-Dawley rats. The clinical signs of thiamine deficiency were apparent after feeding a thiamine-deficient diet for 3 weeks. Thiamine deficiency caused an increase in P450IIE1, which was determined by N-nitrosodimethylamine demethylase assay and immunoquantitation of P450IIE1. This increase in the P450IIE1 level was mainly attributed to thiamine deficiency per se but not to dietary restriction. Ketone bodies were not elevated in thiamine-deficient rats, whereas ketone bodies were elevated and may have served as inducing factors in calorically restricted pair-fed animals. Injections of pyruvate or pyrithiamine in addition to thiamine deficiency did not potentiate the induction effect. On the other hand, thiamine deficiency did not affect the level of P450IIC11 during the 3 weeks of feeding the thiamine-deficient diet. In addition, thiamine deficiency increased cytosolic glutathione S-transferase activity but not steroid isomerase activity. The present study demonstrates the specificity of thiamine deficiency per se in the induction of P450IIE1 which does not involve an increase in the ketone body level. 相似文献
92.
Hyun-Min Shin Chul-Jong Park Jong-Yuk Yi Tae-Yoon Kim Chung-Won Kim 《Pediatric dermatology》1996,13(2):146-147
Abstract: Juvenile xanthogranuloma is a xanthomatous and granulomatous condition that frequently arises before 1 year of age and mainly occurs on the head and trunk. We report a rare solitary juvenile xanthogranuloma on the right palm of a 10-year-old girl, present for one year. This solitary involvement of the palm has been reported only twice before. 相似文献
93.
The monoclonal antibody MAb 1-7-1, which specifically binds to cytochromes P-450IA1 and P-450IA2 in 3-methylcholanthrene-induced rat liver microsomes, was used to identify a cytochrome P-450IA1 homologue in human lung microsomes. Although MAb 1-7-1 had similar affinity constants for human and rat microsomes, the amount bound to human lung microsomes was severalfold lower than that bound to microsomes from untreated rat or rabbit lung and much lower than the amount bound to 3-methylcholanthrene-induced rat lung or liver microsomes. The amount bound to untreated baboon lung microsomes was similar to that bound to human lung microsomes. Three cytochrome P-450IA1-catalyzed activities, 7-ethoxyresorufin O-deethylase, 7-ethoxycoumarin, O-deethylase, and aryl hydrocarbon hydroxylase, were measurable in human lung microsomes, but the cytochrome P-450IA2-dependent activity acetanilide 4-hydroxylase was not. MAb 1-7-1 inhibited, and its binding correlated strongly with, 7-ethoxyresorufin O-deethylase activity (r = 0.92, p less than 0.01) in human lung microsomes. 7-Ethoxyresorufin O-deethylase activities in human lung were similar to those measured in untreated baboon lung but considerably lower than those present in untreated rabbit lung, untreated or 3-methylcholanthrene-induced rat lung and liver, or human liver. We conclude that MAb 1-7-1 recognizes a cytochrome P-450IA1 homologue in human lung and that no cytochrome P-450IA2 homologue is detected. Cytochrome P-450IA1 is expressed in human lung at relatively low levels, similar to those observed in untreated primate (baboon) lung. The majority of the 19 human lung samples examined do not exhibit a permanent polycyclic aromatic hydrocarbon-induced state with respect to this isozyme. 相似文献
94.
95.
The effect of local administration of vasodilative concentrations of the adenosine receptor agonist 2-chloroadenosine (2-CADO) on the hyperemic responses of the pial and parenchymal microcirculations to graded hypercapnia was determined. The cranial window and brain microdialysis-hydrogen clearance techniques were utilized in two groups of isoflurane-anesthetized newborn pigs to measure changes in pial diameters and local CBF, respectively, in response to graded hypercapnia in the absence and presence of 2-CADO. Progressive size-dependent dilations of pial arterioles [small = 41 +/- 7 microns (mean +/- SD), intermediate = 78 +/- 13 microns, and large = 176 +/- 57 microns in diameter] occurred in response to graded hypercapnia alone (PaCO2 = 58 and 98 mm Hg) and to superfusions of 2-CADO (10(-5) M) during normocapnia; the magnitude of the dilative response to each of these stimuli was inversely proportional to vessel size. When hypercapnia was induced concomitantly with 2-CADO superfusion, the dilative effects of each stimulus were directly additive. Similarly, local microdialysis infusion of 10(-5) M 2-CADO, which doubled CBF during normocapnia, did not affect the hyperemic response of the parenchymal circulation to graded hypercapnia (PaCO2 = 69 and 101 mm Hg). Our findings are consistent with the participation of adenosine in the mediation of cerebral hypercapnic hyperemia. If, however, adenosine is not involved in this dilative response, our results indicate that concomitant vascular and neuromodulatory actions induced by adenosine receptor stimulation do not affect the mechanism responsible for the hypercapnic hyperemic response. 相似文献
96.
Membrane-targeting potentiates guanine nucleotide exchange factor CDC25 and SOS1 activation of Ras transforming activity. 总被引:16,自引:2,他引:14
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)
97.
Nephron Sparing Surgery for De Novo Renal Cell Carcinoma in an Allograft Kidney: A Case Report 总被引:1,自引:0,他引:1
Kyun II Park Hitoshi Inoue Choi Jan Kim Tadao Tomoyoshi 《International journal of urology》1997,4(6):611-614
De novo renal cell carcinoma in a renal allograft is rare and has special implications in renal transplant recipients. We describe a patient with a renal allograft who developed a de novo renal cell carcinoma in the functioning renal allograft 258 months after transplantation. The patient underwent enucleation of the tumor because preoperative MRI showed it was well-encapsulated. A DNA banding study showed that the tumor originated from the donor. Indications for conservative renal surgery in renal cell carcinoma have been increasing. Accordingly, 1 option in the treatment of de novo renal cell carcinoma in a functioning renal allograft is enucleation as a method of nephron sparing surgery. 相似文献
98.
Ischemic necrosis of the entire femoral head and rapidly destructive hip disease: potential causative relationship 总被引:6,自引:0,他引:6
Kyung Nam Ryu Eui Jong Kim Myung Chul Yoo Yong Koo Park David J. Sartoris Donald Resnick 《Skeletal radiology》1997,26(3):143-149
Objective. Rapidly destructive hip disease (RDHD) is an uncommon disorder of the hip that has been considered a disease of unknown cause
and distinct from ischemic necrosis of the femoral head. The objective of this study was to investigate ischemic necrosis
of the femoral head as one potential cause of RDHD. Design and patients. In 600 patients who underwent MR imaging of the hip, 20 cases of ischemic necrosis involving the entire femoral head in 18
patients (3%) were retrospectively studied with routine radiography and MR imaging. All patients had surgically confirmed
ischemic necrosis of the femoral head. Results and conclusions. All patients showed rapid destruction of the femoral head on routine radiography and MR imaging as compared with the gradual
onset of clinical symptoms. Plain radiographs showed several bone fragments at the inferomedial aspect of the femoral head
(75%), acetabular erosions (55%), eccentric depression at the lateral articular surface of the femoral head conforming to
the adjacent acetabulum (35%), and mild osteoarthritis (15%). Bone sclerosis was often present at sites of impaction between
the femoral head and the acetabulum. MR imaging showed marked distention of the joint capsule in all cases. In 14 of 20 cases,
the contents of the joint space showed predominantly low or intermediate signal intensity on T1- and T2-weighted images. Ischemic
necrosis involving the entire femoral head may represent one of the causes of RDHD. 相似文献
99.
100.
Bronchial stenosis due to endobronchial tuberculosis: successful treatment with self-expanding metallic stent. 总被引:30,自引:0,他引:30
J K Han J G Im J H Park M C Han Y W Kim Y S Shim 《AJR. American journal of roentgenology》1992,159(5):971-972
Endobronchial tuberculosis is present in 10-40% of patients with active pulmonary tuberculosis, and more than 90% of the patients with endobronchial tuberculosis have some degree of bronchial stenosis. The primary treatment for tuberculous bronchial stenosis is antituberculous chemotherapy combined with steroids, but some patients do not respond well, and more aggressive treatment is needed to restore the patency of the involved bronchus. Balloon dilatation of tuberculous bronchial stenosis has been reported to be successful. However, in our experience, balloon dilatation of the stenotic segment has not significantly improved patients' clinical symptoms except in those with very short segmental stenosis. We describe a case of tuberculous bronchial stenosis that was successfully treated with Gianturco self-expanding metallic stents. 相似文献