全文获取类型
收费全文 | 2337篇 |
免费 | 174篇 |
国内免费 | 28篇 |
专业分类
耳鼻咽喉 | 82篇 |
儿科学 | 120篇 |
妇产科学 | 34篇 |
基础医学 | 278篇 |
口腔科学 | 75篇 |
临床医学 | 282篇 |
内科学 | 484篇 |
皮肤病学 | 58篇 |
神经病学 | 249篇 |
特种医学 | 144篇 |
外科学 | 268篇 |
综合类 | 93篇 |
一般理论 | 1篇 |
预防医学 | 172篇 |
眼科学 | 57篇 |
药学 | 55篇 |
中国医学 | 1篇 |
肿瘤学 | 86篇 |
出版年
2019年 | 21篇 |
2016年 | 18篇 |
2015年 | 24篇 |
2014年 | 46篇 |
2013年 | 105篇 |
2012年 | 64篇 |
2011年 | 60篇 |
2010年 | 56篇 |
2009年 | 76篇 |
2008年 | 77篇 |
2007年 | 94篇 |
2006年 | 69篇 |
2005年 | 63篇 |
2004年 | 68篇 |
2003年 | 74篇 |
2002年 | 64篇 |
2001年 | 62篇 |
2000年 | 61篇 |
1999年 | 63篇 |
1998年 | 78篇 |
1997年 | 71篇 |
1996年 | 40篇 |
1995年 | 41篇 |
1994年 | 42篇 |
1993年 | 45篇 |
1992年 | 47篇 |
1991年 | 49篇 |
1990年 | 58篇 |
1989年 | 71篇 |
1988年 | 68篇 |
1987年 | 73篇 |
1986年 | 50篇 |
1985年 | 46篇 |
1984年 | 34篇 |
1983年 | 31篇 |
1982年 | 23篇 |
1981年 | 25篇 |
1980年 | 26篇 |
1979年 | 24篇 |
1978年 | 21篇 |
1977年 | 21篇 |
1976年 | 24篇 |
1975年 | 21篇 |
1974年 | 27篇 |
1973年 | 30篇 |
1972年 | 17篇 |
1971年 | 19篇 |
1970年 | 21篇 |
1969年 | 20篇 |
1966年 | 22篇 |
排序方式: 共有2539条查询结果,搜索用时 15 毫秒
41.
42.
43.
Aruny JE Lewis CA Cardella JF Cole PE Davis A Drooz AT Grassi CJ Gray RJ Husted JW Jones MT McCowan TC Meranze SG Van Moore A Neithamer CD Oglevie SB Omary RA Patel NH Rholl KS Roberts AC Sacks D Sanchez O Silverstein MI Singh H Swan TL Towbin RB 《Journal of vascular and interventional radiology : JVIR》1999,10(4):491-498
44.
Dixit MP Cabansag MR Piscitelli J Greifer I Silverstein DM 《Pediatric nephrology (Berlin, Germany)》1999,13(2):139-142
Amyloidosis is a complication of long-term hemodialysis treatment. The major histological feature of hemodialysis-associated
amyloidosis (HAA) is the deposition of amyloid fibrils in the affected lesions, due, in part, to elevated serum β2-microglobulin (β2M) levels. In vitro studies reveal that serum immunoglobulin light and heavy chains co-deposit with β2M
in tissues affected by HAA. Only one study of HAA has been performed in young dialysis patients. We therefore assessed risk
factors for HAA in a group (n=30) of young (18.7±0.9 years) patients receiving chronic, uninterrupted hemodialysis using cellulose acetate membranes. All
patients initiated dialysis before reaching 18 years of age. The pre-dialysis serum β2M level was 49.7±3.9 mg/l (normal 0–2.4
mg/l). Since serum albumin was normal (4.3±0.1 mg/dl) and serum protein/albumin was elevated (1.7±0.0, normal 1.2–1.5), indicating
increased circulating protein, we assayed immunoglobulins in the same patients. The serum immunoglobulin levels (expressed
as a percentage of the total level of serum proteins) were elevated (21.3±0.9%, normal 11.1%–21.0%). The Kt/v was 1.37±0.03,
suggesting that the high levels of serum β2M and immunoglobulins were not due to inadequate dialysis in these patients. Patients
with residual renal function (Kr) did display significantly lower serum levels of β2M (33.2±2.3, P=0.03). Furthermore, improved clearance of β2M correlated with higher values of Kr (r=0.914). In contrast, serum levels of immunoglobulin (22.6±3.7, P=0.5) were unaffected by Kr. In addition, there was no correlation between older age at onset of dialysis and serum levels
of either β2M (r=0.107) or immunoglobulins (r=0.321). Finally, the length of time on dialysis had no effect on serum levels of either β2M (r=0.105) or immunoglobulins (r=0.092). Taken together, these results indicate that young hemodialysis patients may be at risk for HAA.
Received: 13 January 1998 / Revised: 1 June 1998 / Accepted: 2 June 1998 相似文献
45.
46.
OBJECTIVE: The purpose of this study was to determine the effect of left-to-right shunting on the resting energy expenditure (REE), total energy expenditure (TEE), and energy intake in a group of 3- to 5-month-old infants with moderate to large unrepaired ventricular septal defects (VSDs) compared with age-matched, healthy infants. METHODS: Eight infants with VSDs and 10 healthy controls between 3 to 5 months of age participated in the study. Indirect calorimetry was used to measure REE and the doubly-labeled water method was used to measure TEE and energy intake. An echocardiogram and anthropometric measurements were performed on all study participants. Daily urine samples were collected at home for 7 days. Samples were analyzed by isotope ratio mass spectrometry. Data were compared using analysis of variance. RESULTS: No significant differences were found in REE (VSD, 42.2 +/- 8.7 kcal/kg/d; control, 43.9 +/- 14.1 kcal/kg/d) or energy intake (VSD, 90.8 +/- 19.9 kcal/kg/d; control, 87.1 +/- 11.7 kcal/kg/d) between the groups. The percent total body water was significantly higher in the VSD infants and the percent fat mass was significantly lower. TEE was 40% higher in the VSD group (VSD, 87.6 +/- 10.8 kcal/kg/d; control, 61.9 +/- 10.3 kcal/kg/d). The difference between TEE and REE, reflecting the energy of activity, was 2.5 times greater in the VSD group. CONCLUSIONS: REE and energy intake are virtually identical between the two groups. Despite this, infants with VSDs have substantially higher TEE than age-matched healthy infants. The large difference between TEE and REE in VSD infants suggests a substantially elevated energy cost of physical activity in these infants. These results demonstrate that, although infants with VSDs may match the energy intake of healthy infants, they are unable to meet their increased energy demands, resulting in growth retardation. 相似文献
47.
Isolation and characterization of propagable cell lines (HUNC) from the androgen-sensitive Dunning R3327H rat prostatic adenocarcinoma 总被引:1,自引:0,他引:1
Presnell SC; Borchert KM; Glover WJ; Gregory CW; Mohler JL; Smith GJ 《Carcinogenesis》1998,19(4):585-590
The Dunning H rat prostate tumor (R3327H) is a widely used experimental
model of human prostatic adenocarcinoma (CaP). The Dunning H tumor has been
characterized as androgen-sensitive, androgen-receptor (AR) positive,
prostate-specific antigen and prostatic acid phosphatase (PAP) positive. To
date, the tumor has been maintained by serial passage in vivo because of
the lack of an in vitro cell line that retains the characteristics of the
in vivo tumor. The objective of the present study was to establish a
propagable cell line from R3327H adenocarcinoma that maintained androgen
sensitivity and expression of AR, PSA and PAP. Tissue harvested from an in
vivo R3327H tumor was dissociated with collagenase and placed into
Richter's improved media (with supplements). A cytokeratin-positive
epithelial cell line (HUNC- E) and a vimentin-positive stromal cell line
(HUNC-S) were generated from the primary culture, subcultured continuously
for >300 days, and passaged >50 times. Survival of the HUNC-E cell
line in vitro depended on several media supplements, including
nicotinamide, insulin, transferrin, selenium and epidermal growth factor
(EGF). HUNC-E cells expressed AR and produced PSA and PAP throughout the
culture period, as confirmed by immunocytochemistry and Western blot
analyses. Addition of 14 nM testosterone (T) or dihydrotestosterone (DHT)
to HUNC-E cells, stimulated DNA synthesis as well as anchorage-independent
growth and PSA production, which demonstrated the androgen-sensitive nature
of the cells in vitro. When HUNC-E and HUNC-S cells were combined in a 3:1
ratio and introduced subcutaneously into syngeneic male hosts, tumors
formed in 2/3 animals with an average latency of 7 months. RT-PCR and
immunocytochemical characterization of the HUNC cell lines revealed that
the cells expressed several growth factors and their cognate receptors,
including HGF, TGF-alpha and the TGF-betas, indicating the establishment of
potential autocrine loops in the neoplastic cells. The HUNC-E and HUNC-S
CaP cell lines, which retain the characteristics of the epithelial and
stromal components of the in vivo R3327H tumor, will allow a more thorough
and informative molecular and biological analysis of prostatic
adenocarcinoma.
相似文献
48.
A study was carried out to find out the effects of prior physical activity, sports participation and prior military training on the incidence of stress fractures among Gentlemen Cadets (GC''s) undergoing military training at Indian Military Academy (IMA). One thousand and fourteen GC''s were followed up for a period of 12 weeks. Thirty-seven GC''s developed stress fractures during the study period. The incidence of stress fractures was significantly higher in GC''s without any prior military training (p=0.0009). They were compared with 100 healthy controls drawn from the study population to study the influence of the other mentioned factors. There was no significant association between prior physical activity and stress fractures (OR=0.74, 95% CL=0.26 to 2.05, p=0.688). There was also no significant relationship between sports participation and stress fractures (OR=0.79. 95% CCL=0.35 to 1.81, p=0.684).KEY WORDS: Risk factors, Stress fractures 相似文献
49.
Galasso JM Stegman LD Blaivas M Harrison JK Ross BD Silverstein FS 《Experimental neurology》2000,161(1):85-95
Macrophage/microglial infiltration is a characteristic feature of brain tumors. The functional role(s) of these cells is complex and could include both trophic and suppressive effects on tumors. Information has recently emerged about the molecular signals that regulate the accumulation and function of monocytes in pathological disorders. Recent data indicate that the chemokine, monocyte chemoattractant protein-1 (MCP-1), a potent monocyte activating and chemotactic factor, is a primary regulator of the macrophage response in brain tumors. We hypothesized that if MCP-1 regulates macrophage/microglial infiltration, then expression of the specific MCP-1 receptor, CCR2, will be induced in peritumoral tissue and/or within brain tumors. Identification of a specific receptor that is preferentially expressed in brain tumors could be important both in terms of tumor biology and as a potential therapeutic target. We used an established experimental gliosarcoma model, induced by intracranial transplantation of cultured 9L cells into adult rat brain, to test this hypothesis. RT-PCR analysis showed high levels of both MCP-1 and CCR2 mRNA and Western blot analysis demonstrated increased CCR2 protein in tumor extracts. Immunocytochemistry showed CCR2 immunoreactive microglia in peritumoral tissue and, unexpectedly, that intrinsic tumor cells, rather than monocytes, were the predominant source of CCR2. These results demonstrate that CCR2 expression is markedly upregulated in this brain tumor model. 相似文献
50.