全文获取类型
收费全文 | 2048篇 |
免费 | 139篇 |
国内免费 | 46篇 |
专业分类
耳鼻咽喉 | 16篇 |
儿科学 | 95篇 |
妇产科学 | 26篇 |
基础医学 | 143篇 |
口腔科学 | 43篇 |
临床医学 | 286篇 |
内科学 | 334篇 |
皮肤病学 | 45篇 |
神经病学 | 57篇 |
特种医学 | 288篇 |
外科学 | 293篇 |
综合类 | 208篇 |
预防医学 | 139篇 |
眼科学 | 18篇 |
药学 | 121篇 |
2篇 | |
中国医学 | 32篇 |
肿瘤学 | 87篇 |
出版年
2022年 | 30篇 |
2021年 | 33篇 |
2020年 | 31篇 |
2018年 | 21篇 |
2017年 | 22篇 |
2016年 | 20篇 |
2015年 | 35篇 |
2014年 | 50篇 |
2013年 | 74篇 |
2012年 | 78篇 |
2011年 | 85篇 |
2010年 | 90篇 |
2009年 | 104篇 |
2008年 | 69篇 |
2007年 | 80篇 |
2006年 | 82篇 |
2005年 | 52篇 |
2004年 | 49篇 |
2003年 | 50篇 |
2002年 | 46篇 |
2001年 | 38篇 |
2000年 | 27篇 |
1999年 | 28篇 |
1998年 | 82篇 |
1997年 | 74篇 |
1996年 | 72篇 |
1995年 | 67篇 |
1994年 | 41篇 |
1993年 | 50篇 |
1991年 | 19篇 |
1990年 | 14篇 |
1989年 | 30篇 |
1988年 | 42篇 |
1987年 | 40篇 |
1986年 | 29篇 |
1985年 | 33篇 |
1984年 | 20篇 |
1983年 | 24篇 |
1982年 | 16篇 |
1980年 | 16篇 |
1977年 | 15篇 |
1976年 | 14篇 |
1963年 | 17篇 |
1960年 | 14篇 |
1959年 | 22篇 |
1958年 | 29篇 |
1957年 | 19篇 |
1956年 | 30篇 |
1955年 | 42篇 |
1954年 | 35篇 |
排序方式: 共有2233条查询结果,搜索用时 15 毫秒
71.
目的研究1个以光敏性癫痫为主要表现的肌阵挛性癫痫伴肌肉破碎红纤维综合征(MERRF)家系的临床特点、遗传学特征。方法整理一个以光敏性癫痫为主要表现的肌阵挛性癫痫伴肌肉破碎红纤维综合征家系的临床表现、辅助检查及影像学资料,分析其临床特点和遗传特征。结果该家系呈母系遗传,共4人(包括先证者3个同辈,1个子代)出现肌阵挛表现,先证者以光敏性癫痫为主要表现,其肌肉活检可见典型的破碎红纤维(RRF),先证者的线粒体DNA提示8344位点由A突变为G。结论 MERRF家系少见,可以光敏性肌阵挛癫痫为主要表现。 相似文献
72.
Blood coagulation is initiated when plasma factor VII(a) binds to its essential cofactor tissue factor (TF) and proteolytically activates factors X and IX. Progressive inhibition of TF activity occurs upon its addition to plasma. This process is reversible and requires the presence of VII(a), catalytically active Xa, Ca2+, and another component that appears to be associated with the lipoproteins in plasma, a lipoprotein-associated coagulation inhibitor (LACI). A protein, LACI(HG2), possessing the same inhibitory properties as LACI, has recently been isolated from the conditioned media of cultured human liver cells (HepG2). Rabbit antisera raised against a synthetic peptide based on the N-terminal sequence of LACI(HG2) and purified IgG from a rabbit immunized with intact LACI(HG2) inhibit the LACI activity in human serum. In a reaction mixture containing VIIa, Xa, Ca2+, and purified LACI(HG2), the apparent half-life (t1/2) for TF activity was 20 seconds. The presence of heparin accelerated the initial rate of inhibition threefold. Antithrombin III alpha alone had no effect, but antithrombin III alpha with heparin abrogated the TF inhibition. LACI(HG2) also inhibited Xa with an apparent t1/2 of 50 seconds. Heparin enhanced the rate of Xa inhibition 2.5-fold, whereas phospholipids and Ca2+ slowed the reaction 2.5-fold. Xa inhibition was demonstrable with both chromogenic substrate (S-2222) and bioassays, but no complex between Xa and LACI(HG2) could be visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Nondenaturing PAGE, however, showed that LACI(HG2) bound to Xa but not to X or Xa inactivated by diisopropyl fluorophosphate. Thus, LACI(HG2) appears to bind to Xa at or near its active site. Bovine factor Xa lacking its gamma-carboxyglutamic acid-containing domain, BXa(-GD), through treatment with alpha-chymotrypsin, was used to further investigate the Xa requirement for VIIa/TF inhibition by LACI(HG2). LACI(HG2) bound to BXa(-GD) and inhibited its catalytic activity against a small molecular substrate (Spectrozyme Xa), though at a rate approximately sevenfold slower than native BXa. Preincubation of LACI(HG2) with saturating concentrations of BXa(-GD) markedly retarded the subsequent inhibition of BXa. The VII(a)/TF complex was not inhibited by LACI(HG2) in the presence of BXa(-GD), and further, preincubation of LACI(HG2) with BXa(-GD) slowed the inhibition of VIIa/TF after the addition of native Xa. The results are consistent with the hypothesis that inhibition of VII(a)/TF involves the formation of a VIIa-TF-XA-LACI complex that requires the GD of XA.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
73.
74.
Single-acquisition chemical-shift imaging of a binary system with use of stimulated echoes 总被引:1,自引:0,他引:1
A method for separating binary chemical-shift components with a single image data acquisition by means of stimulated echoes is demonstrated. With a strategy analogous to the modified Dixon method, three stimulated echoes were acquired to form three complex images. In each of the images, the complex pixel intensities were imparted, by design of the pulse sequence, with a phase factor carrying chemical-shift or field inhomogeneity information. With these three images, true fat/water separation can be obtained in biologic tissues. Studies at high field strength (4.7 T) on a toluene phantom, a pseudo-binary chemical-shift system, were used to evaluate the applicability of the method. Its clinical feasibility was demonstrated on a healthy human subject in a 0.6-T whole-body imaging system. 相似文献
75.
复方甘草酸苷注射液联合钙剂及维生素C治疗慢性荨麻疹45例疗效观察 总被引:2,自引:0,他引:2
目的评价复方甘草酸苷注射液(美能)治疗慢性荨麻疹的疗效和安全性。方法对照组40例,5%葡萄糖注射液(或生理盐水)150ml加入10%葡萄糖酸钙注射液10ml及维生素C注射液2.0g静滴;治疗组45例,在对照组基础上加用复方甘草酸苷注射液20~60ml静滴,两组均1次/d,疗程6周。结果复方甘草酸苷治疗组有效率88.89%,平均起效时间2.1周,明显优于对照组60.00%和4.2周,两组有效率相比差异有显著性(P<0.05)。结论复方甘草酸苷注射液治疗慢性荨麻疹起效时间短,疗效较好。 相似文献
76.
77.
Bradyarrhythmias and Laparoscopy: A Prospective Study of Heart Rate Changes with Laparoscopy 总被引:1,自引:0,他引:1
Paul S. Myles DipRACOG DA 《The Australian & New Zealand journal of obstetrics & gynaecology》1991,31(2):171-173
Cardiac arrhythmias are a common complication of laparoscopy. Brady-arrhythmias (including asystole) may be life-threatening. The recent introduction of new shorter-acting muscle relaxants (atracurium and vecuronium), with their lack of vagolytic activity, may exacerbate this situation. At the Royal Women's Hospital there have been several episodes of severe bradyarrhythmias and/or asystole associated with these relaxants. This study evaluated heart rate changes in 49 women during laparoscopy: 47% of patients had arrhythmias, 30% of these being bradyarrhythmias. Nearly all the episodes occurred during carbon dioxide insufflation or with traction on pelvic structures. The life-threatening nature of this phenomenon should be understood by all anaesthetists and gynaecologists engaged in laparoscopic procedures. 相似文献
78.
79.
80.
Cytogenetic and molecular genetic analysis of tumorigenic human bronchial epithelial cells induced by radon alpha particles 总被引:4,自引:1,他引:4
To establish a cell culture model for lung carcinogenesis, independent
populations of the human papillomavirus 18-immortalized human bronchial
epithelial cell line BEP2D were treated with high linear energy transfer
radon-simulated alpha-particles, expanded and xenotransplanted into Nu/Nu
mice. Six independent cell lines were established from tumors that
developed from three separate radiation treatments as follows: treatment
(Tx) 1 (30 cGy--two doses), H2BT, Tx 2 (30 cGy-- single dose), R30T1L,
R30T2 and R30T3L, Tx 3 (30 cGy--single dose), H1ATN and H1ATBA1.
Cytogenetic analysis revealed common changes in all tumor lines: loss of
the Y chromosome (ch), one of three copies of ch8, one of three copies of
ch14, and one of two copies of ch4p16-pter and ch11p15-pter. Analysis of
polymerase chain reaction-amplified short tandem repeats of informative
loci confirmed the loss of chY in all lines and loss of heterozygosity
(LOH) at eight loci spanning the length of ch8 in all lines from Tx's 1 and
2. Our data support previous studies indicating the presence of tumor
suppressor genes on ch8. LOH also was confirmed on ch14 at locus D14S306 in
all cell lines from Tx 2 and in one of two lines from Tx 3. This region,
14q12-q13, may contain changes in one of the five known somatostatin
receptor genes (SSTR1). No LOH was detected at any of the informative loci
tested for on ch4 or ch11.
相似文献