全文获取类型
收费全文 | 58448篇 |
免费 | 3936篇 |
国内免费 | 1290篇 |
专业分类
耳鼻咽喉 | 465篇 |
儿科学 | 1277篇 |
妇产科学 | 467篇 |
基础医学 | 4412篇 |
口腔科学 | 581篇 |
临床医学 | 8549篇 |
内科学 | 11249篇 |
皮肤病学 | 353篇 |
神经病学 | 3625篇 |
特种医学 | 1840篇 |
外国民族医学 | 7篇 |
外科学 | 7485篇 |
综合类 | 8423篇 |
现状与发展 | 4篇 |
预防医学 | 3588篇 |
眼科学 | 2983篇 |
药学 | 5596篇 |
63篇 | |
中国医学 | 1530篇 |
肿瘤学 | 1177篇 |
出版年
2024年 | 153篇 |
2023年 | 1074篇 |
2022年 | 1868篇 |
2021年 | 2650篇 |
2020年 | 2378篇 |
2019年 | 2043篇 |
2018年 | 2084篇 |
2017年 | 1992篇 |
2016年 | 2046篇 |
2015年 | 2012篇 |
2014年 | 3961篇 |
2013年 | 4245篇 |
2012年 | 3122篇 |
2011年 | 3517篇 |
2010年 | 2629篇 |
2009年 | 2569篇 |
2008年 | 2598篇 |
2007年 | 2643篇 |
2006年 | 2278篇 |
2005年 | 1884篇 |
2004年 | 1632篇 |
2003年 | 1362篇 |
2002年 | 1185篇 |
2001年 | 1085篇 |
2000年 | 895篇 |
1999年 | 803篇 |
1998年 | 703篇 |
1997年 | 731篇 |
1996年 | 602篇 |
1995年 | 665篇 |
1994年 | 584篇 |
1993年 | 506篇 |
1992年 | 533篇 |
1991年 | 464篇 |
1990年 | 442篇 |
1989年 | 385篇 |
1988年 | 387篇 |
1987年 | 354篇 |
1986年 | 321篇 |
1985年 | 361篇 |
1984年 | 346篇 |
1983年 | 208篇 |
1982年 | 290篇 |
1981年 | 226篇 |
1980年 | 206篇 |
1979年 | 172篇 |
1978年 | 147篇 |
1977年 | 89篇 |
1976年 | 81篇 |
1975年 | 56篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
91.
R. K. Vesalainen K. U. O. Tahvanainen T. J. Kaila I. M. Kantola T. A. Kuusela D. L. Eckberg 《Clinical physiology and functional imaging》1997,17(2):135-133
We studied how posture influences the effects of transdermal scopolamine on autonomic cardiovascular regulation in a randomized, double-blind, placebo-controlled crossover study of 10 healthy young volunteers. We recorded the electrocardiogram and auscultatory sphygmomanometric and continuous non-invasive finger arterial pressure (Finapres device) to obtain signals for the beat-by-beat R–R interval and systolic, mean and diastolic pressures. R–R interval and arterial pressure variabilities were characterized by power spectral analysis. Scopolamine increased the mean R–R intervals and reduced arterial pressure in both the supine and the standing positions, but did not affect blood pressure variability. Scopolamine increased the total variability of R–R interval and its mid- (0·07–0·15 Hz) and high- (0·15–0·40 Hz) frequency band power in the standing position during controlled breathing at 0·25 Hz. In the supine position, scopolamine did not affect R–R interval variability. In the deep breathing test, scopolamine increased the maximal expiratory–inspiratory R–R interval ratio. This study showed that low-dose scopolamine increases vagal cardiac inhibition in both supine and standing positions in healthy volunteers. However, scopolamine increases heart rate variability only in the standing position during partial vagal withdrawal. The study also demonstrates that transdermal scopolamine decreases blood pressure in healthy young subjects. 相似文献
92.
Association of angiotensin II type 1 receptor gene polymorphism with essential hypertension 总被引:15,自引:0,他引:15
The renin-angiotensin system is involved in control of blood pressure and salt and fluid homeostasis. Genes for components of this system have been of major focus in research on the causation of the common, complex, polygenic trait, essential hypertension (HT). Association of an A→C variant at nucleotide 1166 of the angiotensin II type 1 receptor (AT1 R) gene with HT, but an absence of linkage of this locus with this disease, has been reported recently. Since confirmation in a different setting is imperative, we performed a cross-sectional case-control study of the A1166C variant in a well-characterized group of 108 Caucasian HT subjects with a strong family history (two affected parents) and early onset disease. Genotyping was by mismatch polymerase chain reaction/ Bfr I restriction fragment length polymorphism analysis. Frequency of the C1166 allele was 0.40 in HTs and 0.29 in normotensives. The difference in genotype (χ2 = 13, P = 0.0015) and allele (χ2 = 5.3, P = 0.02) frequencies between the two groups was significant (odds ratio for CC vs AA+AC = 7.3 [95% CI, 1.9–31.9). The present results implicate the AT1 R gene, or a locus in linkage disequilibrium with the variant tested, in the causation of essential HT. 相似文献
93.
E. Croce M. Golia M. Azzola R. Russo L. Crozzoli S. Olmi C. Pompa M. Borzio 《Surgical endoscopy》1996,10(11):1064-1068
Background: Thirty-three patients were candidates for laparoscopic choledochotomy. The indications for this operation are described.
Methods: The procedure was completed 32 times (97%). We had 29 successful common bile duct (CBD) clearances, three negative explorations,
and one failed clearance which needed to be converted to laparotomy. All the completed procedures ended with primary closure
of the main duct. Median duration of surgery was 180 min (range 100–300), including three associated laparoscopic procedures.
Results: There were three postoperative complications (9.4%), none major. Average postoperative hospital stay was 7.1 days (range
4–14). In May–June 1995 we controlled 31 out of the 32 consecutive patients (one patient was lost to follow-up) who had a
successful laparoscopic choledochotomy from October 1991 to December 1994. Median follow-up was 22 months (range 5–44). Besides
clinical control, 23 patients also had ultrasound (US) controls and 24 had blood tests. Eleven had intravenous cholangiotomography.
Two patients died 11 and 22 months after the operation for unrelated causes and without biliary symptoms. Two patients had
umbilical hernias. One had a small residual asymptomatic stone, which was removed endoscopically. None had signs of postoperative
CBD stricture. At US, CBD was ≤7 mm in 15 patients, 8–10 mm in four patients, and 10–12 mm in three patients. The last group
had preoperative CBD dilation, too. We could compare preoperative and postoperative CBD diameters in 22 patients: 11 had no
change; in nine it decreased; and two had a slight increase (8–10 mm).
Conclusions: We conclude that laparoscopic choledochotomy with primary closure is a very good operation: It has a high success rate and
low morbidity. Mortality is nil so far. Medium-term results are very positive: We had no CBD stricture and only one case of
asymptomatic residual stone, which could have been avoided. Our results suggest that intraductal biliary drainage is useless,
and its specific complications are well known.
Received: 20 October 1995/Accepted: 28 February 1996 相似文献
94.
95.
观察7例慢性哮喘病人胸导管引流治疗前后外周血淋巴细胞内 cAMp/cGMP 值的变化。结果发现,慢性哮喘病人外周血淋巴细胞内 cAMP/cGMP 的值较正常人低(P<0.001);胸导管引流治疗后,哮喘病人外周血淋巴细胞内 cAMP/cGMP 值较治疗前升高(P<0.01)。提示,慢性哮喘病人外周血淋巴细胞功能异常、活性增强,这可能是哮喘发病的重要原因之一。胸导管引流引起的免疫抑制作用,一个重要的机理就是影响淋巴细胞内环核苷酸的代谢,而使淋巴细胞的活性降低,这可能也是胸导管引流治疗慢性哮喘的机理之一。 相似文献
96.
97.
Da-Nian Zhu, Long-Mei Xue, Peng Li. Effect of central muscarine receptor blockade. with DKJ-21 on the blood pressure and heart rote in stress-induced hypertensive rats.
The experiments were performed on Wistar or Sprague-Dawley rats of both sexes divided at random into stress and control groups. The rats in the stress groups were put into cages and subjected to electric foot-shocks and noises for 9-15 days, which caused an increase in blood pressure (BP) and heart rate (HR). In hypertensive rats DKJ-21 (4mg/lml) was injected intravenously (i.v.), and 0.5-1.0h after administration the BP and HR dropped from the high level to normotensive level. In normotensive rats, however, administration of DKJ-21 had no effect on BP or HR. In separate groups of normotensive rats, pretreatment of DKJ-21 (4 mg/l ml, i.v.) blocked the pressor and tachycardiac effect induced by microinjection of physostigmine (0.4μg/0.1 /μl/site), corticosterone (40μg/0.1μl/site) or aldosterone (40 μg/0.1 μl/site) into the rostral ventrolateral medulla (rVLM). Furthermore, DKJ-21 also attenuated the enhancement of the pressor response to stimulation of the defense area in the midbrain, which was induced by microinjection of drugs (mentioned above) into the rVLM. These results indicate that i.v. DKJ-21 can selectively block the muscarinic receptors in the rVLM in stress-induced hypertensive rats, which suggests that abnormal enhancement of cholinergic mechanism in the rVLM may be related to hypertensive effects of corticoids in this area. 相似文献
The experiments were performed on Wistar or Sprague-Dawley rats of both sexes divided at random into stress and control groups. The rats in the stress groups were put into cages and subjected to electric foot-shocks and noises for 9-15 days, which caused an increase in blood pressure (BP) and heart rate (HR). In hypertensive rats DKJ-21 (4mg/lml) was injected intravenously (i.v.), and 0.5-1.0h after administration the BP and HR dropped from the high level to normotensive level. In normotensive rats, however, administration of DKJ-21 had no effect on BP or HR. In separate groups of normotensive rats, pretreatment of DKJ-21 (4 mg/l ml, i.v.) blocked the pressor and tachycardiac effect induced by microinjection of physostigmine (0.4μg/0.1 /μl/site), corticosterone (40μg/0.1μl/site) or aldosterone (40 μg/0.1 μl/site) into the rostral ventrolateral medulla (rVLM). Furthermore, DKJ-21 also attenuated the enhancement of the pressor response to stimulation of the defense area in the midbrain, which was induced by microinjection of drugs (mentioned above) into the rVLM. These results indicate that i.v. DKJ-21 can selectively block the muscarinic receptors in the rVLM in stress-induced hypertensive rats, which suggests that abnormal enhancement of cholinergic mechanism in the rVLM may be related to hypertensive effects of corticoids in this area. 相似文献
98.
肝门胆管癌近年有增多趋势,本文报告我院1975年~1985年间肝门胆管癌60例,占全部肝外胆管癌82例之73.1%,占同期全部胆道手术3626例之1.65%。临床表现主要有三型:1)阻塞性黄疸29例,其中25例曾误诊为肝炎;2)急性胆管炎12例;3)长期胆道疾病14例,其他5例。本组行B超检查19例,ERCP10例,PTC39例。最后诊断根据PTC和/或ERCP,剖腹术及病理检查结果。 56例施行了手术治疗,仅6例施行肿瘤连同半肝切除,姑息性肝胆管内引流15例,外引流23例,其他方法12例。平均存活时间:6例切除组24.5月,48例姑息手术组8.7月,未手术的4例为5月。文中强调早期诊断,凡40岁以上出现阻塞性黄疸或“传染性肝炎”均须警惕胆管癌,进行B超,CT,ERCP或PTC检查,文中强调PTC是诊断本病重要手段,可选择进行右左肝管PTC。本病应争取手术切除,不能切除者行肝胆管内引流或外引流,二者疗效无明显差别。 相似文献
99.
M. O. Hassan O. T. Al Shafie W. J. Johnston 《Clinical physiology and functional imaging》1993,13(5):519-523
Summary. Eleven normotensive diabetics with noninsulin-dependent diabetes mellitus (NIDDM) (mean age 52.5 SD 8.2 years) and 11 controls (mean age 47.4 SD 8.9 years) had their ambulatory blood pressure and heart rate recorded non-invasively by the Oxford Medilog System in standard hospital conditions. The results were averaged as hourly means of systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MAP), and heart rate (HR) for the 24-h period and similarly for the ‘awake’ period (14.16 h) and the ‘asleep’ period (8–10 h). Hourly means for diabetics and controls showed no differences in blood pressure and heart rate over the 24 h. During sleep, control subjects showed a significant drop in SBP (P < 0.001), DBP (P < 0.001), MAP (P < 0.001) and HR (P < 0.001). However, this nocturnal dip in blood pressure could not be demonstrated in the diabetic group. Blood pressure variability was significantly increased in diabetics compared to controls during waking hours (P < 0.01). These results indicate that in noninsulin-dependent diabetics during sleep there is loss of the nocturnal dip of BP seen in normal subjects, and they have increased BP variability. These may be contributing factors to the development of hypertension and the accelerated target organ damage (TOD) seen in diabetes., 相似文献
100.
Iwar Klime Antonian Vraana Jaroslav Kune Elena eboUkovaA Zdena Dobe ovaa Pavel tolba Josef Zicha 《Blood pressure》1995,4(3):137-142
Hereditary hypertriglyceridemic rats (hHTg) were developed as a new genetic model for the study of relationships between blood pressure (BP) and metabolic abnormalities. This strain has been produced by selective inbreeding from Wistar rats according to the rise of plasma triglycerides induced by a high-sucrose diet. Though hHTg rats display hypertriglyceridemia, impaired glucose tolerrance, hyperinsulinemia, insulin resistance and increased BP even without nutritional stimuli, high sucrose feeding further aggravates these symptoms. High plasma triglycerides levels in hHTg rats seem to be a consequence of their hyperproduction. Impaired insulin action is responsible for the defective glucoregulation in this strain. The loss of insulin responsiveness might be due to a reduction in the number of glucose transporters. Highly significant relationships among plasma triglycerides, ouabain-resistant Na+ transport and BP were demonstrated in the hHTg rats. Segregating populations (F2 hybrids) should be used for genetic analysis of the primary role of lipid and/or ion transport abnormalities in the pathogenesis of this form of genetic hypertension. 相似文献