全文获取类型
收费全文 | 5934篇 |
免费 | 205篇 |
国内免费 | 77篇 |
专业分类
电工技术 | 365篇 |
综合类 | 92篇 |
化学工业 | 975篇 |
金属工艺 | 157篇 |
机械仪表 | 157篇 |
建筑科学 | 157篇 |
矿业工程 | 51篇 |
能源动力 | 155篇 |
轻工业 | 464篇 |
水利工程 | 63篇 |
石油天然气 | 24篇 |
武器工业 | 12篇 |
无线电 | 637篇 |
一般工业技术 | 857篇 |
冶金工业 | 1518篇 |
原子能技术 | 138篇 |
自动化技术 | 394篇 |
出版年
2023年 | 35篇 |
2022年 | 77篇 |
2021年 | 109篇 |
2020年 | 71篇 |
2019年 | 67篇 |
2018年 | 69篇 |
2017年 | 62篇 |
2016年 | 75篇 |
2015年 | 110篇 |
2014年 | 116篇 |
2013年 | 248篇 |
2012年 | 209篇 |
2011年 | 278篇 |
2010年 | 228篇 |
2009年 | 209篇 |
2008年 | 242篇 |
2007年 | 229篇 |
2006年 | 225篇 |
2005年 | 174篇 |
2004年 | 139篇 |
2003年 | 161篇 |
2002年 | 120篇 |
2001年 | 145篇 |
2000年 | 115篇 |
1999年 | 162篇 |
1998年 | 577篇 |
1997年 | 374篇 |
1996年 | 264篇 |
1995年 | 155篇 |
1994年 | 141篇 |
1993年 | 141篇 |
1992年 | 75篇 |
1991年 | 65篇 |
1990年 | 66篇 |
1989年 | 63篇 |
1988年 | 59篇 |
1987年 | 39篇 |
1986年 | 54篇 |
1985年 | 47篇 |
1984年 | 47篇 |
1983年 | 31篇 |
1982年 | 43篇 |
1981年 | 33篇 |
1980年 | 36篇 |
1979年 | 29篇 |
1978年 | 23篇 |
1977年 | 35篇 |
1976年 | 50篇 |
1975年 | 17篇 |
1973年 | 22篇 |
排序方式: 共有6216条查询结果,搜索用时 12 毫秒
61.
62.
This paper proposes an efficient method to develop requirement specifications for Plant Control Software (PCSW) using software-component-based prototypes. Prior to this proposal, domain analyses were conducted on existing PCSWs, and their functions were classified into “similar functions” and “individual functions”. Then PCSW Software Components (PSC: PCSW Software Component, PSCs: PCSW Software Components) were developed to correspond to these functions. PSCs as parameter-style components were developed in order to satisfy the clients’ (we define clients as owners, managers and operators of plants) requirements. A support environment for developing requirement specifications was developed. The environment consists of the Prototype Development Tool (PDT), the Behavior Check Simulator (BCS) and the Requirement Specification Development Tool (RSDT). The method consists of four steps. In the first step, PDT is used to define the parameters to customize PSCs and to compose a PCSW prototype by setting these parameters to PSCs. In the second step, BCS is used to execute the composed PCSW prototype and check its behavior and relevancy against the clients’ expectations. In the third step, steps 1 and 2 are repeated until the behavior of the PCSW prototype satisfies the clients’ requirements. Finally, a requirement specification is developed from the PCSW prototype which fully reflects the clients’ requirements. In order to evaluate the proposed method, it has been applied in five development cases. A Requirement Coverage of 91%, a Requirement Revision Rate of 6%, a PSC Reuse Rate of 92% and a LOC Reuse Rate of 83% have been achieved. In addition, a reduction of 55% in the amount of time required to develop requirement specifications has been achieved. These results indicate that the proposed method has sufficient capability to develop an exhaustive and an adequate PCSW requirement specification. And the developed PSCs have sufficient functions and capability to compose PCSW prototypes, and the support environment is capable of shortening the time taken to develop requirement specifications. 相似文献
63.
64.
Athermal silica-based arrayed-waveguide grating multiplexer 总被引:4,自引:0,他引:4
Inoue Y. Kaneko A. Hanawa F. Takahashi H. Hattori K. Sumida S. 《Electronics letters》1997,33(23):1945-1947
A temperature dependent channel wavelength shift in a silica-based arrayed-waveguide grating multiplexer is successfully suppressed from 0.95 to 0.05 nm in the 0-85°C temperature range, which means that it can be used in practical WDM systems without the need for temperature control 相似文献
65.
Matano T. Takai Y. Takahashi T. Sakito Y. Fujii I. Takaishi Y. Fujisawa H. Kubouchi S. Narui S. Arai K. Morino M. Nakamura M. Miyatake S. Sekiguchi T. Koyama K. 《Solid-State Circuits, IEEE Journal of》2003,38(5):762-768
A 1-Gb/s/pin 512-Mb DDRII SDRAM has been developed using a digital delay-locked loop (DLL) and a slew-rate-controlled output buffer. The digital DLL has a frequency divider for DLL input, performs at an operating frequency of up to 500 MHz at 1.6 V, and provides internal clocking with 50% duty-cycle correction. The DLL has a current-mirror-type interpolator, which enables a resolution as high as 14 ps, needs no standby current, and can operate at voltages as low as 0.8 V. The slew-rate impedance-controlled output buffer circuit reduces the output skew from 107 to 10 ps. This SDRAM was tested using a 0.13-/spl mu/m 126.5-mm/sup 2/ 512-Mb chip. 相似文献
66.
67.
O van der Heijden HC Chiu TC Park H Takahashi VA LiVolsi JI Risinger JC Barrett A Berchuck AC Evans K Behbakht AW Menzin PC Liu I Benjamin MA Morgan SA King SC Rubin J Boyd 《Canadian Metallurgical Quarterly》1998,23(4):243-247
The degree and nature of patient involvement in consultations with health professionals influences problem and needs recognition and management, and public accountability. This paper suggests a framework for understanding the scope for patient involvement in such consultations. Patients are defined as co-producers of formal health services, whose potential for involvement in consultations depends on their personal rights, responsibilities and preferences. Patients' rights in consultations are poorly defined and, in the National Health Service (NHS), not legally enforceable. The responsibilities of patients are also undefined. I suggest that these are not to deny, of their own volition, the rights of others, which in consultations necessitate mutuality of involvement through information-exchange and shared decision-making. Preferences should be met insofar as they do not militate against responsibilities and rights. 相似文献
68.
K Arai S Yamamura T Hanyu HE Takahashi H Umezu H Watanabe T Abo 《Canadian Metallurgical Quarterly》1996,157(11):5170-5177
Murine collagen-induced arthritis (CIA) is known as a T cell-mediated autoimmune disease, although autoantibodies are also suspected to be associated with the onset of the disease. To determine the origin of such T cells in the joints of mice with CIA, their phenotypic properties as well as those of T cells in other immune organs were examined in DBA/1 mice. Since a significant number of mononuclear cells (MNC) was also yielded by the joints of normal DBA/1 mice, the properties of these T cells were examined in parallel. When CIA was induced by an intradermal injection of type II collagen at the base of the tail, the numbers of MNC yielded by the regional lymph nodes and the foot joints were doubled. Interestingly, regardless of the onset of CIA, the joints were always comprised of unique T cell populations, including IL-2(R)alpha- beta+ T cells, gammadelta T cells, CD8alpha+ beta- cells, and CD44+ L-selectin- cells. All these properties coincide with those of extrathymic T cells in liver and intestine. In the case of gammadelta T cells in joints, Vgamma and Vdelta usages were unique and different from those in the other organs. More importantly, Vgamma and Vdelta usages in gammadelta T cells in the joints of normal mice and in those of mice with CIA were essentially the same. Taken together with the expression of recombination-activating gene-1 and -2 mRNAs by MNC in mice with CIA, these findings raise the possibility that the joints have their own resident T cells that are extrathymically generated in situ. 相似文献
69.
OBJECTIVE: To investigate HLA class II allele associations with autoantibody responses to Ro/SS-A and La/SS-B among Japanese subjects. METHODS: Haplotype and allele distributions, along with molecular polymorphisms, of HLA class II genes were analyzed by polymerase chain reaction-restriction fragment length polymorphism in 41 Japanese women with precipitating autoantibodies to Ro/SS-A and/or La/SS-B. RESULTS: Among women with both Ro/SS-A and La/SS-B antibodies, the HLA class II haplotype DRB1*08032/DQA1*0103/DQB1*0601 and DRB1*08032 allele showed significantly increased frequencies compared with patients with anti-Ro/SS-A alone or with normal controls. All women with both anti-Ro/SS-A and anti-La/SS-B, but not those with anti-Ro/SS-A alone, carried DRB1 alleles that shared the same amino acid residues at positions 14-31 and 71 of the hypervariable regions of the DRB1 chain. All anti-Ro/SS-A positive women carried 1 or 2 alleles of DQB1*06 and DQB1*03 subtypes that shared the same amino acid residues at positions 71-77 of the DQB1 chain. HLA class II allele distributions did not differ among 3 anti-Ro/SS-A positive groups with different disease expressions, i.e., patients with systemic lupus erythematosus, patients with primary Sj?gren's syndrome, and women with no apparent symptoms of rheumatic disease. CONCLUSION: HLA class II allele distributions differ among anti-Ro/SS-A positive subjects according to the presence or absence of coexisting anti-La/SS-B antibodies, but not according to disease expression. Our findings suggest that different HLA class II molecules might control the development of anti-Ro/SS-A and/or anti-La/SS-B antibodies in the autoimmune response to the Ro/SS-A-La/SS-B complex. 相似文献
70.
Y Nakazawa K Mitsui Y Hirai K Takahashi T Ishikawa 《Canadian Metallurgical Quarterly》1994,35(4):197-205
The purpose of this experiment was to investigate histo-pathologically the pulpal reaction to a glass-ionomer/resin (Geristore) restoration system in human teeth. Black's class I cavities were prepared in 22 human teeth; these were divided into 2 groups, one with the Geristore after cavity was cleaned with 10% NaOCl solution and 3% H2O2 solution (Group G) and the other with the Geristore after the cavity was applied with Mirage-Bond (Group MG). The treated teeth were observed clinically over 90 days after operation. They were then extracted for histological examination. No unpleasant symptoms were noted. A few pathological changes were observed. No histo-pathological score differences were observed between groups G and MG. The average evaluation score of pathological results in both groups G and MG were excellent. Microorganisms observed in the cavity dentin of the group G was fewer than in group MG. In some cases, microorganisms were observed along the dentin walls. In conclusion, the pulpal injury due to this Geristore restoration system was slight, and the system was considered to be safe for the pulp and clinically useful. 相似文献