首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   22721篇
  免费   1506篇
  国内免费   255篇
耳鼻咽喉   380篇
儿科学   358篇
妇产科学   487篇
基础医学   3692篇
口腔科学   503篇
临床医学   1953篇
内科学   4429篇
皮肤病学   617篇
神经病学   1713篇
特种医学   1265篇
外科学   2839篇
综合类   179篇
一般理论   4篇
预防医学   1100篇
眼科学   710篇
药学   2149篇
中国医学   326篇
肿瘤学   1778篇
  2023年   173篇
  2022年   540篇
  2021年   864篇
  2020年   424篇
  2019年   630篇
  2018年   748篇
  2017年   592篇
  2016年   827篇
  2015年   1155篇
  2014年   1286篇
  2013年   1558篇
  2012年   2194篇
  2011年   2090篇
  2010年   1239篇
  2009年   968篇
  2008年   1323篇
  2007年   1220篇
  2006年   1114篇
  2005年   1003篇
  2004年   816篇
  2003年   677篇
  2002年   614篇
  2001年   409篇
  2000年   356篇
  1999年   267篇
  1998年   114篇
  1997年   72篇
  1996年   61篇
  1995年   67篇
  1994年   53篇
  1993年   50篇
  1992年   125篇
  1991年   108篇
  1990年   96篇
  1989年   97篇
  1988年   82篇
  1987年   70篇
  1986年   58篇
  1985年   56篇
  1984年   34篇
  1983年   31篇
  1982年   21篇
  1981年   12篇
  1980年   16篇
  1979年   16篇
  1978年   20篇
  1977年   14篇
  1975年   15篇
  1974年   25篇
  1973年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Reduction mammaplasty by central pedicle flap with short submammary scar   总被引:2,自引:0,他引:2  
Reduction mammaplasty was performed in 30 patients by combining the central pedicle flap method with the short submammary scar (3-S) technique to avoid the common drawbacks of currently popular dermoglandular procedures. Reduction was accomplished by using perforating vascular branches from the pectoralis major muscle and its fascia supplying the nipple and breast parenchyme instead of the subdermal plexus. The central vascular pedicle supplying the nipple-areola complex was preserved. Only the periphery of the breast parenchyme was resected circumferentially, with the exception of the inferolateral portion, so as not to injure the sensory nerve. The remaining breast parenchyme was preserved in an inverted cone shape. The nipple-areola complex was safely transposed with great freedom, and the amount of resection was accurately adjusted for symmetry. No cases of nipple-areola complex sensory change occurred postoperatively, and lactation is possible because of preservation of the lactiferous ducts. The length of postoperative scars was reduced by using the short submammary scar technique. We believe this combined method is ideal in patients requiring resections ranging from 200 to 600 g per breast with good skin elasticity and moderate degree of ptosis.Presented at the Sixth Asian Pacific Congress of the International Confederation for Plastic and Reconstructive Surgery, in Seoul, Korea, October 1993.  相似文献   
32.
Ten (E)-and (Z)-isomers of 2-phenylcyclopropylamine (PCA), 1-Me-PCA, 2-Me-PCA, N-Me-PCA, and N, N-diMe-PCA and fifteeno , m, p isomers of (E)-PCA with substituents of Me, Cl, F, OMe, OH were synthesized in this laboratory and tested for the inhibition of rat brain mitochondrial MAO-A and MAO-B. The effects of substituents, their positions, and stereochemistry on the inhibition were assessed for the compounds with substituents at cyclopropyl and amino groups and QSAR analyses were performed using the potency data of ring-substituted compounds. The best correlated QSAR equations are as follows: pI50=0.804 Π2 Blo−1.069 Blm+0.334 Lp−1.709 HDp+7.897 (r=0.945, s=0.211, F=16.691, p=0.000) for the inhibition of MAO-A; pI50=1.815 π-0.825 Π2 R+0.900 Es2+0.869 Es3+0.796 Es4−0.992 HDp+0.562 HAo+3.893 (r=0.982, s=0.178, F=23.351, p=0.000) for the inhibition of MAO-B. Based on the potency difference between stereoisomers of cyclopropylamine-modified compounds and on QSAR results, it is proposed that the active sites of MAO-A are composed of one deep hydrophobic cavity near para position, two hydrophobic cavities interacting with Me group, a hydrophobic area accomodating phenyl and cyclopropyl backbone, steric boundaries, a hydrogen-acceptor site near para position, and an amino group binding site and that in addition to the same two hydrophobic cavities, hydrophobic area, steric boundaries, hydrogen-acceptor site, and amino group binding site, another steric boundary near para position and a hydrogen donating site near ortho position constitute active sites of MAO-B.  相似文献   
33.
Summary Cavernous sinus thrombosis (CST) is rarely seen clinically as a complication of infectious processes since the discovery of penicillin. At the present time, dental abscess is an uncommon cause of CST. We now report our experiences with a 60-year-old diabetic male, who developed CST 38 days after extraction of an infected upper third molar tooth. The importance of eradicating regional cervicofacial foci of infection is stressed.  相似文献   
34.
Paralytic toxicity was detected by tetrodotoxin (TTX) bioassay in all 15 specimens of the xanthid crab Lophozozymus pictor collected from northern Taiwan in 1993. The average toxicity of crab specimens was 921 ± 231 (mean ± S.E.) mouse units. The toxin of crab was partially purified and then identified. It was found that the crab toxin contained TTX and gonyautoxin. The ratio of TTX to gonyautoxin for crab toxin was about 9:1.  相似文献   
35.
We report an uncommon case of solitary, small hepatic angiosarcoma that was initially considered as a hemangioma. We present the imaging findings, with an emphasis on the initial and follow-up CT and MR findings, as well as report on the more suggestive findings of angiosarcoma than those of a hemangioma.  相似文献   
36.
A patient with chronic cerebral paragonimiasis began to have new motor seizures of the right face manifested by clonic contractions that occurred several hundred times a day, consistent with simple partial status epilepticus. Ictal electroencephalogram discharges started from the left frontal region and then spread to the left hemisphere with left frontal maximum. But clinical seizures were limited to the right face. The frequent partial seizures were controlled by the intravenous infusion of phenytoin. Brain magnetic resonance imaging showed multiple conglomerated round nodules with encephalomalacia in the left temporal and occipital lobes. Applying the technique of ictal-interictal single-photo emission computed tomography subtraction, the authors were able to localize the focal ictal-hyperperfusion on left precentral cortex adjacent to the lesions that correspond to the anatomical distribution of left face motor area.  相似文献   
37.
Computer algorithms for rotational therapy beams, in most cases, perform dose calculations by summing stored fixed beam data at finite angular steps. Such an algorithm, based on the Bentley beam model, was evaluated by comparing calculations with measured data for an 18-MV x-ray beam. Measurements were made in a specially constructed cylindrical water phantom of 15-cm radius using a 0.1-cm3 ionization chamber for an arc of 180 degrees and for a field size of 7.2 X 7.2 cm2 at 100-cm source-axis distance. This study revealed that the Bentley beam model, with fixed beams summed every 10 degrees, predicts the dose in the treatment volume, centered about the isocenter, with an accuracy of approximately 2%. However, dose at depths between the phantom surface and the treatment volume could be underestimated by as much as 10% (3% of isocenter). This was shown to be partially due to the truncated tails of the off-axis profiles in the Bentley model, which extend only 8 mm outside the edge of the radiation field, and the large angular increment of integration (10 degrees). Using beam profiles extending to 4 cm outside the edge of the radiation field and angular steps of 5 degrees or less for summation of fixed beams reduced errors to less than 5%. Therefore, extended beam profiles and smaller angular steps for summing fixed beams are recommended for photon rotation calculation when increased accuracy is required.  相似文献   
38.
This study investigated whether previous contact with mental illness affected the attitudes to mental illness (AMI) of general student nurses in Hong Kong — the contact hypothesis. We employed a quasi-experimental design. We compared the attitudes to mental illness of students who had previous contact with mental illness through having taken a psychiatric secondment with those who had not taken a psychiatric secondment. Also, we compared the AMI of: students who had taken other courses related to mental illness with those who had not; those who had a family history of mental illness with those who had not; and those who lived with a mentally ill relative with those who did not. We found that previous contact with mental illness had no significant effect on the attitudes to mental illness of the students. In other words our findings do not support the contact hypothesis. Our sample expressed positive general attitudes to mental illness when presented with general issues about mental illness. However, their attitudes were less positive when presented with specific issues about mental illness that might impinge upon their daily lives. We discuss the implications of these findings for mental health nursing practice, education and research.  相似文献   
39.
40.
Kun Hwang  MD  PHD    Jin Yi Han  MD  MA    Se Il Lee  MD  DMSC 《Dermatologic surgery》2004,30(4):562-565
Background. Malignant changes in burn scars occasionally develop, the majority being squamous cell carcinoma. Malignant melanomas (MMs) arising in burn scars occur rarely.
Objective. To present the case of a patient with a multiple MM developed at different burn scar areas.
Methods. A case report and review of literature are given.
Results. One was a large pigmented nodular lesion with central ulceration on right flank. It was widely excised and revealed lentigo MM. After that, we took notice another small pigmented lesion on right arm. It was also reported lentigo MM.
Conclusion. This case provided a valuable lesson. Another kind of tumor may be present even if one tumor is found by pathologic observation, especially in burn scar patients. Clinicians should carefully observe burn scars, chronic ulcers, and other pigmented lesions.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号