全文获取类型
收费全文 | 2400篇 |
免费 | 5篇 |
国内免费 | 3篇 |
专业分类
综合类 | 1篇 |
化学工业 | 22篇 |
金属工艺 | 4篇 |
机械仪表 | 1篇 |
建筑科学 | 1篇 |
能源动力 | 2篇 |
轻工业 | 1篇 |
无线电 | 7篇 |
一般工业技术 | 16篇 |
冶金工业 | 2344篇 |
自动化技术 | 9篇 |
出版年
2021年 | 2篇 |
2019年 | 2篇 |
2016年 | 2篇 |
2015年 | 4篇 |
2014年 | 1篇 |
2013年 | 10篇 |
2012年 | 2篇 |
2011年 | 1篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2007年 | 3篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 7篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 82篇 |
1998年 | 736篇 |
1997年 | 450篇 |
1996年 | 275篇 |
1995年 | 158篇 |
1994年 | 113篇 |
1993年 | 159篇 |
1992年 | 21篇 |
1991年 | 17篇 |
1990年 | 26篇 |
1989年 | 18篇 |
1988年 | 15篇 |
1987年 | 19篇 |
1986年 | 21篇 |
1985年 | 13篇 |
1983年 | 3篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1980年 | 21篇 |
1979年 | 1篇 |
1978年 | 5篇 |
1977年 | 53篇 |
1976年 | 116篇 |
1975年 | 1篇 |
1955年 | 4篇 |
排序方式: 共有2408条查询结果,搜索用时 15 毫秒
31.
MA Skinner MG Schlatter SA Heifetz JL Grosfeld 《Canadian Metallurgical Quarterly》1993,128(8):849-53; discussion 853-4
OBJECTIVE: To review the clinical presentation, treatment, and outcome in a series of children with ovarian neoplasms. DESIGN: A retrospective review of the medical records in a case series of 29 girls with ovarian neoplasms. The length of follow-up ranged from 6 months to 7 1/2 years and averaged 3.0 years in the girls with malignant tumors. SETTING: The patients were treated at a large referral children's hospital. PATIENTS: Twenty-nine girls with ovarian neoplasms were treated from 1976 to 1992. The average age of the patients was 10 years and ranged from 2 to 16 years. MAIN OUTCOME MEASURES: The principal outcomes examined were mortality and surgical morbidity. RESULTS: The most common presenting symptoms for these ovarian tumors in pediatric patients included chronic abdominal pain, an abdominal mass, or distention. Three girls presented with precocious puberty or hirsutism. In 27 cases, the tumor was a primary ovarian lesion. In two patients, the ovarian mass was the presenting finding for a stage IV non-Hodgkin's lymphoma. Seventeen tumors were benign and 12 were malignant. Tumors originating from the germ-cell line predominated (n = 17). Seven of the 10 ovarian malignant neoplasms were stage I at the time of diagnosis. All but one of the girls with malignant tumors received either adjunctive radiation therapy or multiple-agent chemotherapy. Two girls with sex cord/stromal cell tumors who presented with stage I disease ultimately developed widespread metastases. Both girls with large epithelial tumors survived. All of the girls with benign tumors and seven (70%) of 10 with malignant lesions survived. CONCLUSION: Ovarian tumors are unusual lesions in the pediatric population. Unlike in adults, such neoplasms generally originate from the germ-cell line. Whereas most ovarian tumors in girls are benign, some children have malignant tumors that are very aggressive and do not respond well to adjuvant therapy. In particular, malignant sex cord/stromal cell tumors, even when they present at an early stage, may behave unpredictably. 相似文献
32.
33.
34.
35.
The effects of acute pentobarbital treatment were assessed using a complex operant test battery containing five tasks in which correct performance is thought to depend upon processes associated with short-term memory and attention [delayed-matching-to-sample (DMTS)], color and position discrimination [conditioned position responding (CPR)], motivation [progressive ratio (PR)], time perception [temporal response differentiation (TRD)], and learning [incremental repeated acquisition (IRA)]. Adult, male rhesus monkeys were tested 15 min after IV injection of saline or pentobarbital (1, 3, 5.6, 10, or 15 mg/kg). Behavioral endpoints measured included percent task completed, response rate or latency, and response accuracy. The order of task sensitivity to disruption by PBT was TRD > IRA = DMTS = PR > CPR, in which sensitivity was defined as a significant disruption in any aspect of task performance. PBT slowed response rates at 10.0 and/or 15.0 mg/kg in all tasks. Accuracy was decreased in the TRD task at > or = 5.6 mg/kg but doses of > or = 10.0 mg/kg were required to decrease accuracy in the IRA, DMTS, and CPR tasks. Thus, behavior thought to model time perception (TRD) was more sensitive than behavior modeling learning (IRA), short-term memory and attention (DMTS), and motivation (PR). CPR was the least sensitive behavior. Because pentobarbital exerts its effects at least in part via GABA systems, the effects in the current study were compared with those of a previous study of the acute effects of diazepam. The two compounds exerted fundamentally different effects on operant test battery performance. 相似文献
36.
Phenotypic analysis of antigen-specific T lymphocytes 总被引:4,自引:0,他引:4
JD Altman PA Moss PJ Goulder DH Barouch MG McHeyzer-Williams JI Bell AJ McMichael MM Davis 《Canadian Metallurgical Quarterly》1996,274(5284):94-96
Identification and characterization of antigen-specific T lymphocytes during the course of an immune response is tedious and indirect. To address this problem, the peptide-major histocompatability complex (MHC) ligand for a given population of T cells was multimerized to make soluble peptide-MHC tetramers. Tetramers of human lymphocyte antigen A2 that were complexed with two different human immunodeficiency virus (HIV)-derived peptides or with a peptide derived from influenza A matrix protein bound to peptide-specific cytotoxic T cells in vitro and to T cells from the blood of HIV-infected individuals. In general, tetramer binding correlated well with cytotoxicity assays. This approach should be useful in the analysis of T cells specific for infectious agents, tumors, and autoantigens. 相似文献
37.
MG Niemia?towski FN Toka E Malicka Gieryńska I Spohr de Faundez A Schollenberger 《Canadian Metallurgical Quarterly》1996,44(5-6):373-378
An 11-year global WHO campaign for eradication of smallpox finished in October 1977 as the result of Edward Jenner's primary success in 1796, who for the first time applied human vaccination against variola virus (VARV). The 200th anniversary of this happening is a good occasion to summarize the current status of the knowledge about the role of B and T lymphocytes in the control of orthopoxvirus infections. This short review concentrates on general characteristics of orthopoxviruses and the immune response to infection, mainly by vaccinia virus (VV) and ectromelia virus (EV). 相似文献
38.
Presentation of our experience in three cases of urocolpos (acquired pudendal lip fusion), a series numerically equivalent to the total number of cases published until now. All patients in our series were older women and presented complete fusion of the small pudendal lips, with only a small pointed puncture in the lower part of the vulva. The main clinical signs and symptoms in our series were: urinary infection in 100%, false incontinence in 66% due to output of urine retained in the vagina, a symptom that has not been described earlier, and acute urine retention in 33%. All patients were successfully treated by means of surgical loosening of the fusioned lips and application of topical estrogens. An analysis is made of clinical and pathoanatomical features which differentiate this entity from the sclerotic and atrophic lichen. Finally, an etiopathogenic hypothesis is raised to explain the fusion acquired by the small pudendal lips in the urocolpos. 相似文献
39.
40.
NV Tat'ianko LL Gromashevskaia AD Vovk MG Kasatkina OV Liashok VI Matiash SP Iasinovy? IaN Kovgan 《Canadian Metallurgical Quarterly》1996,(5-6):119-122
In this paper, characterization is given of clinical and biochemical features of VH B course against the background of narcomania. Recordable in such patient populations are high percentage of delta hepatitis (14.2%), unusual severity of the intoxication syndrome, protracted course with exacerbations (12.2%) and recurrences (8%), outcome being a chronic hepatitis (14.2%), slower normalization of biochemical indicators, persistently low ratio of AIAT activity in diluted and whole blood sera. The persistence of viral markers in drug addicts discharged from the hospital (68%) is fraught with danger of spreading viral hepatitis of prophylactic measures are not strictly observed. 相似文献