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   24133篇
  免费   1810篇
  国内免费   79篇
耳鼻咽喉   395篇
儿科学   842篇
妇产科学   375篇
基础医学   2473篇
口腔科学   534篇
临床医学   2167篇
内科学   5303篇
皮肤病学   555篇
神经病学   1281篇
特种医学   1183篇
外国民族医学   1篇
外科学   4584篇
综合类   447篇
一般理论   15篇
预防医学   1168篇
眼科学   822篇
药学   2045篇
中国医学   38篇
肿瘤学   1794篇
  2023年   223篇
  2022年   401篇
  2021年   1010篇
  2020年   474篇
  2019年   818篇
  2018年   946篇
  2017年   612篇
  2016年   648篇
  2015年   679篇
  2014年   1016篇
  2013年   1185篇
  2012年   1747篇
  2011年   1715篇
  2010年   889篇
  2009年   832篇
  2008年   1296篇
  2007年   1219篇
  2006年   1145篇
  2005年   989篇
  2004年   896篇
  2003年   760篇
  2002年   655篇
  2001年   595篇
  2000年   556篇
  1999年   501篇
  1998年   192篇
  1997年   159篇
  1996年   166篇
  1995年   158篇
  1994年   144篇
  1993年   107篇
  1992年   272篇
  1991年   285篇
  1990年   255篇
  1989年   224篇
  1988年   221篇
  1987年   235篇
  1986年   206篇
  1985年   190篇
  1984年   120篇
  1983年   134篇
  1982年   91篇
  1981年   78篇
  1980年   66篇
  1979年   132篇
  1978年   80篇
  1977年   73篇
  1975年   62篇
  1974年   65篇
  1973年   88篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
This paper describes the problems and solutions in using 18 MeV linear accelerator, with minimum 6 MeV electron capability, for total skin irradiation for mycosis fungoides. The 6 MeV electron energy can be degraded to acceptable electron energy of 3.2 MeV by interposing a plexiglass sheet of 9.6 mm in the beam. To minimize the bremsstrahlung, the degrading plexiglass should be kept away from the machine head. A wide area with uniform dose distribution over single plane can be achieved by using dual fields but homogenous dose distribution over irregular body surface cannot be achieved mainly because of self-shielding. The nails and the ocular lens can be easily shielded from the low energy electrons with 1.5 mm lead shield.  相似文献   
92.
An infant girl with elevated blood lactate, pyruvate, and plasma branched-chain amino acids was diagnosed with dihydrolipoamide dehydrogenase (E3; dihydrolipoamide: NAD+ oxidoreductase, EC 1.8.1.4) deficiency. Activities of the pyruvate dehydrogenase complex and E3 from patient were 26 and 2% of controls in blood lymphocytes, and 11 and 14% in cultured skin fibroblasts, respectively. Western blot analysis demonstrated that the amount of E3 protein in fibroblasts from the patient and her father was about half of controls, while Northern blot analysis showed normal amounts of E3 RNA. DNA sequencing of cloned full-length E3 cDNAs from the patient revealed two mutations in separate alleles. One is a single base insertion of an extra adenine in the last codon of the leader peptide sequence (TAC-->TAAC) leading to a nonsense mutation which results in the premature termination of the precursor E3 polypeptide (Y35X). The other is a missense mutation due to substitution of guanine for adenine, causing an Arg-->Gly substitution at amino acid 460 of the mature protein (R460G) which triggers the loss of E3 activity probably by structural change in the E3 dimer. DNA sequencing of E3 cDNAs from the parents demonstrated that the nonsense mutation was inherited from the father and the missense mutation was inherited from the mother.   相似文献   
93.
Mucormycosis is an uncommon fungal infection, occurring mainly in patients with acidosis, chronic illnesses and malignancies. The most frequent site of involvement in patients of hematological malignancies is the respiratory tract. Isolated subcutaneous localization of mucormycosis in such patients is extremely rare. We report a case of a young patient of non-Hodgkin's lymphoma on chemotherapy who presented with a subcutaneous swelling on the anterior aspect of right thigh. Fine needle aspiration cytology (FNAC) smears from the swelling revealed numerous characteristic broad, irregularly contoured and pleomorphic hyphae of mucormycosis. This fungus seldom grows in culture and confirmation of the diagnosis depends on cytological or histological examination of infected tissues. Our case report documents a rare site of isolated mucormycosis infection and emphasizes the role of FNAC as a simple, rapid, accurate, and useful method of diagnosing fungal infections.  相似文献   
94.
Leukaemic myeloid and lymphoid cell N-acetyl beta-D glucosaminidase (hexosaminidase) enzymes were fractionated by Fast Protein Liquid Chromatography (FPLC) using high-resolution ion exchange (Mono-S and Mono-Q), gel filtration (Superose-6) and chromatofocusing (Mono-P) columns. Although only one molecular weight species was detected in haemopoietic cells, with an apparent mass of 129 kD, "isoenzyme" variants defined by differences in molecular charge were considerably more diverse than previously thought. Separation of the major Hex forms (A and B) by chromatofocusing indicated that intermediate (I) components were present in most acute leukaemias irrespective of lineage supporting the concept that the I form is a non-specific marker of haemopoietic immaturity. Substrate and inhibitor studies further revealed that leukaemic cell hexosaminidases hydrolyse galactopyranosides at significantly lower rates than glucopyranosides and that the hydrolysis of N-acetyl beta-D glucosamine is inhibited by both glucosamine and galactosamine products.  相似文献   
95.
Prospective payment systems using the diagnostic related group (DRG) mechanism are being phased in for Medicare inpatient hospital care. The purpose of this study was to examine a common neurosurgical procedure (001), craniotomy without trauma, and characterize the cost dynamics of this DRG. All patients (n = 50) treated in this DRG at the Long Island Jewish Medical Center during 1983 had their financial charges exclusive of physician fees examined. The findings were: (a) each hospital service category had wide charge variances around the mean; (b) emergency (ER) admissions were 200% more expensive than nonemergency (non-ER) admissions; (c) ER admissions seemed to have no greater severity of illness than non-ER admissions, but had a significantly different referral pattern (i.e., admission from the ER to a nonneurosurgical service with a subsequent neurosurgical referral); (d) this DRG when grouped into clinical "subproducts" (i.e., craniotomy for tumor, hematoma, hydrocephalus, aneurysm, benign cyst, and other) showed marked charge differences; and (e) the most expensive 25% of patients had five times higher charges than the least expensive 25% for both ER and non-ER admissions. This type of financial analysis may give surgeons a methodology with which to address the problems of cost containment in a more serious manner.  相似文献   
96.
Lasers in Medical Science - To evaluate the effect of various media and Iridex MicroPulse P3 (MP3) probe angles on the power output from the Cyclo G6 Glaucoma Laser (G6) System. A laser power meter...  相似文献   
97.
98.
99.
Congenital constriction band syndrome has varied clinical presentations ranging from small, incomplete skin deep constriction band to in utero amputation. Pseudarthrosis of underlying bone most commonly tibia has been reported by many authors. We report the first case of congenital pseudarthrosis of the femur with congenital constriction band syndrome. Nine-day-old female presented with the constriction band in the left thigh with open pseudarthrosis of the femur. The left femur had gross recurvatum deformity and the posterior apex of the pseudarthrosis was exposed via skin ulceration. She had an ipsilateral paralytic clubfoot. She was treated with single-stage excision of constriction band and Z-plasty. Spontaneous union of the femur was achieved at 3 months. Procurvatum deformity of the femur improved gradually over 3 years. This happens to be the first and only reported case of congenital pseudarthrosis of the femur with sciatic nerve palsy due to congenital constriction band.  相似文献   
100.
BackgroundPortal vein embolization before liver resection is considered the therapy of choice for patients with inadequate future liver remnants. The concept of radioembolization with Yttrium-90 to achieve the same goal has limited data.MethodsWe retrospectively compared patients who underwent portal vein embolization and Yttrium-90 lobectomy before resection of hepatocellular carcinoma in patients with chronic liver disease.ResultsSeventy-three patients underwent portal vein embolization and 22 patients underwent Yttrium-90. Forty-seven percent of patients before portal vein embolization required additional procedures for tumor control, and 27% of patients after Yttrium-90 required additional procedure to mainly induce further hypertrophy. Both therapies achieved the goal of future liver remnants >40%, but the degree of hypertrophy was significantly higher in Yttrium-90 patients (63% for Yttrium-90, 36% for portal vein embolization, P < .01). Tumor response was significantly better with Yttrium-90, achieving complete response in 50% of patients. Resectability rate was higher after portal vein embolization (85% for portal vein embolization, 64% for Yttrium-90, P = .03). Tumor progression was the most common reason precluding surgery. Complete tumor control was the reason not to pursue surgery in 18% of patients after Yttrium-90.ConclusionBoth preoperative portal vein embolization and Yttrium-90, increases liver resectability rates by inducing hypertrophy of future liver remnants in patients with hepatocellular carcinoma and chronic liver disease. Yttrium-90 lobectomy achieved better tumor control and provided more time to assess therapy response, optimizing the indication for surgery.  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