全文获取类型
收费全文 | 22406篇 |
免费 | 1283篇 |
国内免费 | 161篇 |
专业分类
耳鼻咽喉 | 283篇 |
儿科学 | 598篇 |
妇产科学 | 759篇 |
基础医学 | 2374篇 |
口腔科学 | 659篇 |
临床医学 | 1785篇 |
内科学 | 4394篇 |
皮肤病学 | 472篇 |
神经病学 | 1082篇 |
特种医学 | 822篇 |
外国民族医学 | 11篇 |
外科学 | 3907篇 |
综合类 | 561篇 |
现状与发展 | 2篇 |
一般理论 | 11篇 |
预防医学 | 2079篇 |
眼科学 | 622篇 |
药学 | 2004篇 |
中国医学 | 151篇 |
肿瘤学 | 1274篇 |
出版年
2023年 | 251篇 |
2022年 | 788篇 |
2021年 | 1147篇 |
2020年 | 624篇 |
2019年 | 790篇 |
2018年 | 1082篇 |
2017年 | 645篇 |
2016年 | 665篇 |
2015年 | 673篇 |
2014年 | 929篇 |
2013年 | 1098篇 |
2012年 | 1575篇 |
2011年 | 1720篇 |
2010年 | 989篇 |
2009年 | 716篇 |
2008年 | 1004篇 |
2007年 | 1057篇 |
2006年 | 975篇 |
2005年 | 925篇 |
2004年 | 808篇 |
2003年 | 794篇 |
2002年 | 747篇 |
2001年 | 282篇 |
2000年 | 259篇 |
1999年 | 281篇 |
1998年 | 126篇 |
1997年 | 119篇 |
1996年 | 131篇 |
1995年 | 124篇 |
1994年 | 161篇 |
1993年 | 94篇 |
1992年 | 225篇 |
1991年 | 265篇 |
1990年 | 240篇 |
1989年 | 214篇 |
1988年 | 206篇 |
1987年 | 200篇 |
1986年 | 184篇 |
1985年 | 150篇 |
1984年 | 84篇 |
1983年 | 55篇 |
1982年 | 35篇 |
1981年 | 26篇 |
1980年 | 24篇 |
1975年 | 25篇 |
1973年 | 28篇 |
1969年 | 24篇 |
1968年 | 24篇 |
1967年 | 25篇 |
1966年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Rammurti T Kamble George B Selby Martha Mims Mohamed A Kharfan-Dabaja Howard Ozer James N George 《Biology of blood and marrow transplantation》2006,12(5):506-510
Iron overload presenting as exacerbation of hepatic graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation has not been previously described. We report 6 patients with established hepatic GVHD in whom iron overload (median serum ferritin, 7231 mug/dL; median transferrin saturation, 77%) resulting from a lifetime median of 20 units of packed red blood cell transfusions was manifested by worsening of liver function. Liver biopsies performed in 4 patients confirmed severe iron overload and also hepatic GVHD. Analysis for the C282Y and H63D hemochromatosis gene mutation was negative for the homozygous state in all 6 patients. Erythropoietin-assisted phlebotomy resulted in normalization of liver function at a median of 7 months and of serum ferritin at a median of 11 months. Immunosuppressive therapy was successfully tapered in all 4 patients who completed the phlebotomy program, and this supported the impression that iron overload, rather than GVHD, was the principal cause of liver dysfunction. At a median follow-up of 50 months (range, 18-76 months) from the transplantation and 25 months (range, 5-36 months) from ferritin normalization, all 4 patients require maintenance phlebotomy. We conclude that iron overload can mimic GVHD exacerbation, thus resulting in unnecessary continuation or intensification of immunosuppressive therapy for GVHD, and that maintenance phlebotomy is necessary after successful iron-reduction therapy. 相似文献
12.
The possible reversal by calcium of the inhibitory action of verapamil on the atrioventricular (AV) node was investigated in anesthetized, atropinized dogs, with cardiac pacing. The His bundle potentials were recorded by endocavitory electrode and the AV node effective refractory period measured by the extrastimulus method. Calcium infusion was effective against the impairment of AV nodal conduction induced by verapamil, provided it remained moderate: the gradual rise in the plasma calcium concentration counteracted the effects of an infusion of verapamil on conduction time and effective refractory period in the AV node, as long as it did not exceed 5 mmol/L. However, beyond this level, calcium appeared less and less capable of reversing the effects of verapamil. Thus, the protective action of calcium had a bell-shaped dose-response curve, with the optimum at 5 mmol/L. This biphasic influence is consistent with the opposite opinions previously given concerning the antagonism between calcium and calcium blockers, depending on whether hypercalcemia brought into play was mild or major. In any case, the prominent role played by calcium in the slow inward current in the AV node accounts for the antagonism, observed in vivo, between calcium and verapamil. The pacemaker activity of the sinoatrial (SA) node was less influenced by both calcium blocker and calcium. 相似文献
13.
The concentration of microsomal cytochromes P-450, and of protein in the homogenate, cytosol and microsomes were measured in the liver, kidney and duodenal mucosa of healthy well-fed male and female camels, sheep and goats. For comparison, data from the liver of male and female rats were also obtained. The protein concentrations in the tissues of adult animals were broadly similar in the four species. The concentration of cytochromes P-450 was highest in the liver, followed by the kidney, then the duodenal mucosa in all the species. No cytochromes P-450 were detected in the tissues of immature (less than 1 mo) male goats, whereas the female goat had the highest concentrations of these enzymes in the liver and kidney when compared with the respective tissues in the other species studied. Males had higher activity of cytochromes P-450 than females in the three tissues, except in the duodenal mucosa of sheep, where males had lower activity than females. In camel liver and sheep kidney, the amount of cytochromes P-450 were similar in the two sexes. The present results suggest that the mature female goat is the species best equipped to handle xenobiotics which are detoxified by the cytochromes P-450 and other drug metabolizing enzymes in diseased or malnourished animals is suggested as these two conditions are known to modify drug metabolizing enzymes. 相似文献
14.
The influence of protein solubilisation, conformation and size on the burst release from poly(lactide-co-glycolide) microspheres. 总被引:5,自引:0,他引:5
Gayle Duncan Thomas J Jess Farahidah Mohamed Nicholas C Price Sharon M Kelly Christopher F van der Walle 《Journal of controlled release》2005,110(1):34-48
Encapsulation of proteins in poly(lactide-co-glycolide) microspheres via emulsion is known to cause insoluble protein aggregates. Following protein emulsification and encapsulation in PLGA microspheres, we used circular dichroism to show that the recoverable soluble protein fraction also suffers subtle conformational changes. For a panel of proteins selected on the basis of molecular size and structural class, conformational stability measured by chemical denaturation was not indicative of stability during emulsion-encapsulation. Partial loss of structure was observed for alpha-helical proteins released from freeze-dried microspheres in aqueous buffer, with dramatic loss of structure for a beta-sandwich protein. The addition of sucrose (a lyoprotectant) did not prevent the loss of protein conformation upon encapsulation. Therefore, the conformational changes seen for the released soluble protein fraction originates during emulsification rather than microsphere freeze-drying. Analysis of the burst release for all proteins in buffer containing denaturant or surfactant showed that the degree of protein solubilisation was the dominant factor in determining the initial rate and extent of release. Our data for protein release into increasing concentrations of denaturing buffer suggest that the emulsion-denatured protein fraction remains insoluble; this fraction may represent the protein loss encountered upon comparison of protein encapsulated versus protein released. 相似文献
15.
16.
Youness El harrech Hassan Jira Jaouad Chafiki Mohamed Ghadouane Ahmed Ameur Mohamed Abbar 《Actas urologicas espa?olas》2009,33(1):93-96
Nutcracker syndrome is caused by compression of the left renal vein between the aorta and the superior mesenteric artery where it passes in the fork formed at the bifurcation of these arteries. The phenomenon results in left renal venous hypertension. The syndrome is manifested by left flank and abdominal pain, with or without unilateral haematuria. The nutcracker syndrome has been treated in various ways. We report one case of the syndrome and discuss the place of surveillance in its management. 相似文献
17.
Synthesis of 2-(Hydrazinocarbonylthio)-acetic Acids and Cyclization to 3-Aminothiazolidine-2,4-diones N-mono- or N,N-disubstituted hydrazines are reacted with carbonyl sulfide, triethylamine and halogenoacetic acids to yield the 2-(hydrazinocarbonylthio) acetic acids 1 , which are cyclizised to yield the 3-aminothiazolidine-2,4-diones 2 by dicyclohexylcarbodiimide. 相似文献
18.
M Massoud M el Tagui W Saleh 《The Journal of the Egyptian Public Health Association》1991,66(3-4):387-395
The sensitive ELISA assay was used to measure the specific rubella virus IgG & IgM, and also the total IgM in the umbilical cord sera taken from 182 Saudi mothers during delivery in the Maternity Department at Al Ali General Hospital, Riyadh, Saudi Arabia. Nearly 84.6% (154 out of 182) Saudi women tested were found to be immune to rubella virus. 相似文献
19.
Sudden coronary death in Glasgow: the severity and distribution of chronic coronary atherosclerotic stenoses. 下载免费PDF全文
A detailed analysis of the extent of coronary artery atherosclerosis was made in 92 white subjects (66 men and 26 women) who died suddenly from ischaemic heart disease. Stenoses resulting in loss of greater than or equal to 75% of luminal cross sectional area (significant stenosis) were found in 90 subjects and these were more extensive in the proximal coronary tree than in the distal. Thirty nine per cent had triple vessel disease, 37% had double vessel disease, and 23% had single vessel disease. In addition one man had an isolated significant stenosis affecting the left main coronary artery. The frequency of significant stenoses in the left main coronary artery was greater in men than in women. The arteries that were least affected were the distal branches of the right coronary artery. A notable feature was the widespread nature of the coronary atherosclerosis: only 26 of the total of 1840 segments of coronary artery examined in the 92 victims could be described as having a normal intima (less than or equal to 10% loss of the area within the internal elastic lamina). 相似文献
20.
I Ilardi S C Shiddo H H Mohamed C Mussa A S Hussein C S Mohamed K Bile A Sebastiani C Bianchini S Sanguigni 《Transactions of the Royal Society of Tropical Medicine and Hygiene》1987,81(2):336-338
About 85% of the population of two Somali communities harboured soil-transmitted intestinal nematodes and/or protozoa. The commonest parasite (75% in the Lafoole institution and 59% in the Afgoye institution) was Trichuris trichiura. Mixed infections were common. The source of infection is contaminated fields around dwelling quarters, because of indiscriminate defaecation. One of the factors responsible for the higher incidence of hookworm in Lafoole (45%) compared with Afgoye (1.5%) may be the different soil character of the surrounding fields. 相似文献